diff --git a/cameleer-server-app/src/main/java/com/cameleer/server/app/license/RetentionPolicyApplier.java b/cameleer-server-app/src/main/java/com/cameleer/server/app/license/RetentionPolicyApplier.java
new file mode 100644
index 00000000..33cd4afd
--- /dev/null
+++ b/cameleer-server-app/src/main/java/com/cameleer/server/app/license/RetentionPolicyApplier.java
@@ -0,0 +1,119 @@
+package com.cameleer.server.app.license;
+
+import com.cameleer.server.core.license.LicenseGate;
+import com.cameleer.server.core.license.LicenseLimits;
+import com.cameleer.server.core.runtime.Environment;
+import com.cameleer.server.core.runtime.EnvironmentRepository;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Qualifier;
+import org.springframework.context.event.EventListener;
+import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.scheduling.annotation.Async;
+import org.springframework.stereotype.Component;
+
+import java.util.List;
+
+/**
+ * Recomputes ClickHouse per-environment TTL on every {@link LicenseChangedEvent}.
+ *
+ * <p>Spec §4.3 — when a license is installed, replaced, or expires, the effective
+ * retention cap may change. For each (table, env) pair this listener emits one
+ * {@code ALTER TABLE … MODIFY TTL <expr> WHERE environment = '<slug>'} statement
+ * with {@code effective = min(licenseCap, env.configuredRetentionDays)}.</p>
+ *
+ * <p>ClickHouse 22.3+ supports per-row TTL via the {@code WHERE} predicate; the
+ * project's CH version (24.12) is well above that floor. ClickHouse failures are
+ * logged and swallowed — TTL recompute is best-effort and must not propagate
+ * to the originating license install/revalidate path.</p>
+ *
+ * <p>NOTE: {@code route_diagrams} has no TTL clause in {@code init.sql} — it's a
+ * {@code ReplacingMergeTree} keyed on content_hash, not a time-series table —
+ * so it is intentionally excluded here. {@code server_metrics} has no
+ * {@code environment} column (server-wide) so it is also excluded; its 90-day
+ * cap is fixed in the schema.</p>
+ */
+@Component
+public class RetentionPolicyApplier {
+
+    private static final Logger log = LoggerFactory.getLogger(RetentionPolicyApplier.class);
+
+    /** (table, time column, license cap key, env-configured-days extractor). */
+    private record TableSpec(String table, String timeCol, String capKey, Extractor extractor) {}
+
+    @FunctionalInterface
+    private interface Extractor {
+        int days(Environment env);
+    }
+
+    /**
+     * Tables with a TTL clause AND an {@code environment} column in {@code init.sql}.
+     * Verified against the schema at task time — keep in sync if new retention-bound
+     * tables are added.
+     */
+    static final List<TableSpec> SPECS = List.of(
+            new TableSpec("executions",           "start_time",   "max_execution_retention_days", Environment::executionRetentionDays),
+            new TableSpec("processor_executions", "start_time",   "max_execution_retention_days", Environment::executionRetentionDays),
+            new TableSpec("logs",                 "timestamp",    "max_log_retention_days",       Environment::logRetentionDays),
+            new TableSpec("agent_metrics",        "collected_at", "max_metric_retention_days",    Environment::metricRetentionDays),
+            new TableSpec("agent_events",         "timestamp",    "max_metric_retention_days",    Environment::metricRetentionDays)
+    );
+
+    private final LicenseGate gate;
+    private final EnvironmentRepository envRepo;
+    private final JdbcTemplate clickhouseJdbc;
+
+    public RetentionPolicyApplier(LicenseGate gate,
+                                  EnvironmentRepository envRepo,
+                                  @Qualifier("clickHouseJdbcTemplate") JdbcTemplate clickhouseJdbc) {
+        this.gate = gate;
+        this.envRepo = envRepo;
+        this.clickhouseJdbc = clickhouseJdbc;
+    }
+
+    @EventListener(LicenseChangedEvent.class)
+    @Async
+    public void onLicenseChanged(LicenseChangedEvent event) {
+        LicenseLimits limits;
+        try {
+            limits = gate.getEffectiveLimits();
+        } catch (Exception e) {
+            log.warn("Skipping TTL recompute — could not read effective limits: {}", e.getMessage());
+            return;
+        }
+
+        List<Environment> envs;
+        try {
+            envs = envRepo.findAll();
+        } catch (Exception e) {
+            log.warn("Skipping TTL recompute — could not load environments: {}", e.getMessage());
+            return;
+        }
+
+        log.info("License changed (state={}) — recomputing TTL across {} environment(s) and {} table(s)",
+                event.state(), envs.size(), SPECS.size());
+
+        for (Environment env : envs) {
+            for (TableSpec spec : SPECS) {
+                int cap = limits.get(spec.capKey);
+                int configured = spec.extractor.days(env);
+                int effective = Math.min(cap, configured);
+                // Slugs are regex-validated `^[a-z0-9][a-z0-9-]{0,63}$`, so the replacement
+                // is defense-in-depth — single quotes can never be present.
+                String envLiteral = env.slug().replace("'", "''");
+                String sql = "ALTER TABLE " + spec.table
+                        + " MODIFY TTL toDateTime(" + spec.timeCol
+                        + ") + INTERVAL " + effective + " DAY DELETE"
+                        + " WHERE environment = '" + envLiteral + "'";
+                try {
+                    clickhouseJdbc.execute(sql);
+                    log.info("Applied TTL: table={} env={} days={} (cap={}, configured={})",
+                            spec.table, env.slug(), effective, cap, configured);
+                } catch (Exception e) {
+                    log.warn("Failed to apply TTL for table={} env={}: {}",
+                            spec.table, env.slug(), e.getMessage());
+                }
+            }
+        }
+    }
+}
diff --git a/cameleer-server-app/src/test/java/com/cameleer/server/app/license/RetentionPolicyApplierTest.java b/cameleer-server-app/src/test/java/com/cameleer/server/app/license/RetentionPolicyApplierTest.java
new file mode 100644
index 00000000..566755a4
--- /dev/null
+++ b/cameleer-server-app/src/test/java/com/cameleer/server/app/license/RetentionPolicyApplierTest.java
@@ -0,0 +1,194 @@
+package com.cameleer.server.app.license;
+
+import com.cameleer.server.core.license.LicenseGate;
+import com.cameleer.server.core.license.LicenseInfo;
+import com.cameleer.server.core.license.LicenseState;
+import com.cameleer.server.core.runtime.Environment;
+import com.cameleer.server.core.runtime.EnvironmentRepository;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.ArgumentCaptor;
+import org.springframework.jdbc.core.JdbcTemplate;
+
+import java.time.Instant;
+import java.util.List;
+import java.util.Map;
+import java.util.UUID;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatCode;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.doThrow;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+class RetentionPolicyApplierTest {
+
+    EnvironmentRepository envRepo;
+    JdbcTemplate ch;
+    LicenseGate gate;
+    RetentionPolicyApplier applier;
+
+    @BeforeEach
+    void setUp() {
+        envRepo = mock(EnvironmentRepository.class);
+        ch = mock(JdbcTemplate.class);
+        gate = new LicenseGate();
+        applier = new RetentionPolicyApplier(gate, envRepo, ch);
+    }
+
+    private static Environment env(String slug, int execDays, int logDays, int metricDays) {
+        return new Environment(
+                UUID.randomUUID(), slug, slug, false, true,
+                Map.of(), null, "slate", Instant.now(),
+                execDays, logDays, metricDays);
+    }
+
+    private void licenseWithCaps(int execCap, int logCap, int metricCap) {
+        LicenseInfo info = new LicenseInfo(
+                UUID.randomUUID(), "default", null,
+                Map.of(
+                        "max_execution_retention_days", execCap,
+                        "max_log_retention_days", logCap,
+                        "max_metric_retention_days", metricCap
+                ),
+                Instant.now(),
+                Instant.now().plusSeconds(86400),
+                0);
+        gate.load(info);
+    }
+
+    private static LicenseChangedEvent ev() {
+        return new LicenseChangedEvent(LicenseState.ACTIVE, null);
+    }
+
+    @Test
+    void onChange_emitsAlterPerTablePerEnv() {
+        licenseWithCaps(30, 30, 30);
+        Environment dev = env("dev", 30, 30, 30);
+        when(envRepo.findAll()).thenReturn(List.of(dev));
+
+        applier.onLicenseChanged(ev());
+
+        // 5 retention-bound tables defined in SPECS
+        ArgumentCaptor<String> sql = ArgumentCaptor.forClass(String.class);
+        verify(ch, times(RetentionPolicyApplier.SPECS.size())).execute(sql.capture());
+
+        List<String> all = sql.getAllValues();
+        // every statement is an ALTER TABLE … MODIFY TTL … WHERE environment = 'dev'
+        assertThat(all).allSatisfy(s -> {
+            assertThat(s).startsWith("ALTER TABLE ");
+            assertThat(s).contains("MODIFY TTL toDateTime(");
+            assertThat(s).contains(" DAY DELETE");
+            assertThat(s).endsWith(" WHERE environment = 'dev'");
+        });
+
+        // Sanity-check the per-table time column wiring
+        assertThat(findFor(all, "executions"))
+                .contains("toDateTime(start_time)");
+        assertThat(findFor(all, "processor_executions"))
+                .contains("toDateTime(start_time)");
+        assertThat(findFor(all, "logs"))
+                .contains("toDateTime(timestamp)");
+        assertThat(findFor(all, "agent_metrics"))
+                .contains("toDateTime(collected_at)");
+        assertThat(findFor(all, "agent_events"))
+                .contains("toDateTime(timestamp)");
+    }
+
+    @Test
+    void chFailure_doesNotPropagate() {
+        licenseWithCaps(30, 30, 30);
+        when(envRepo.findAll()).thenReturn(List.of(env("dev", 30, 30, 30)));
+        doThrow(new RuntimeException("ch down")).when(ch).execute(anyString());
+
+        assertThatCode(() -> applier.onLicenseChanged(ev()))
+                .doesNotThrowAnyException();
+
+        // listener still attempted every (env, table) pair despite failures
+        verify(ch, times(RetentionPolicyApplier.SPECS.size())).execute(anyString());
+    }
+
+    @Test
+    void multipleEnvs_emitsPerEnvAlter() {
+        licenseWithCaps(30, 30, 30);
+        when(envRepo.findAll()).thenReturn(List.of(
+                env("dev", 30, 30, 30),
+                env("prod", 30, 30, 30)
+        ));
+
+        applier.onLicenseChanged(ev());
+
+        ArgumentCaptor<String> sql = ArgumentCaptor.forClass(String.class);
+        int expected = RetentionPolicyApplier.SPECS.size() * 2;
+        verify(ch, times(expected)).execute(sql.capture());
+
+        long devCount = sql.getAllValues().stream()
+                .filter(s -> s.endsWith("WHERE environment = 'dev'")).count();
+        long prodCount = sql.getAllValues().stream()
+                .filter(s -> s.endsWith("WHERE environment = 'prod'")).count();
+        assertThat(devCount).isEqualTo(RetentionPolicyApplier.SPECS.size());
+        assertThat(prodCount).isEqualTo(RetentionPolicyApplier.SPECS.size());
+    }
+
+    @Test
+    void effectiveDaysIsMinOfCapAndConfigured_capWins() {
+        // env wants 30 days but license caps at 7 → expect INTERVAL 7 DAY
+        licenseWithCaps(7, 7, 7);
+        when(envRepo.findAll()).thenReturn(List.of(env("dev", 30, 30, 30)));
+
+        applier.onLicenseChanged(ev());
+
+        ArgumentCaptor<String> sql = ArgumentCaptor.forClass(String.class);
+        verify(ch, times(RetentionPolicyApplier.SPECS.size())).execute(sql.capture());
+        assertThat(sql.getAllValues())
+                .allSatisfy(s -> assertThat(s).contains("INTERVAL 7 DAY DELETE"));
+    }
+
+    @Test
+    void effectiveDaysIsMinOfCapAndConfigured_configuredWins() {
+        // env wants 3 days, license allows up to 7 → expect INTERVAL 3 DAY
+        licenseWithCaps(7, 7, 7);
+        when(envRepo.findAll()).thenReturn(List.of(env("dev", 3, 3, 3)));
+
+        applier.onLicenseChanged(ev());
+
+        ArgumentCaptor<String> sql = ArgumentCaptor.forClass(String.class);
+        verify(ch, times(RetentionPolicyApplier.SPECS.size())).execute(sql.capture());
+        assertThat(sql.getAllValues())
+                .allSatisfy(s -> assertThat(s).contains("INTERVAL 3 DAY DELETE"));
+    }
+
+    @Test
+    void mixedCapAndConfigured_perTable() {
+        // distinct caps per axis; env exec=10, log=2, metric=50
+        // exec  : min(20, 10) = 10
+        // log   : min(20, 2)  = 2
+        // metric: min(20, 50) = 20
+        licenseWithCaps(20, 20, 20);
+        when(envRepo.findAll()).thenReturn(List.of(env("dev", 10, 2, 50)));
+
+        applier.onLicenseChanged(ev());
+
+        ArgumentCaptor<String> sql = ArgumentCaptor.forClass(String.class);
+        verify(ch, times(RetentionPolicyApplier.SPECS.size())).execute(sql.capture());
+        List<String> all = sql.getAllValues();
+
+        assertThat(findFor(all, "executions")).contains("INTERVAL 10 DAY");
+        assertThat(findFor(all, "processor_executions")).contains("INTERVAL 10 DAY");
+        assertThat(findFor(all, "logs")).contains("INTERVAL 2 DAY");
+        assertThat(findFor(all, "agent_metrics")).contains("INTERVAL 20 DAY");
+        assertThat(findFor(all, "agent_events")).contains("INTERVAL 20 DAY");
+    }
+
+    /** Pick the single SQL statement that targets the given table. */
+    private static String findFor(List<String> all, String table) {
+        String prefix = "ALTER TABLE " + table + " ";
+        return all.stream()
+                .filter(s -> s.startsWith(prefix))
+                .findFirst()
+                .orElseThrow(() -> new AssertionError("no SQL for table " + table + " in: " + all));
+    }
+}