diff --git a/src/lib/db/feature-type-store.ts b/src/lib/db/feature-type-store.ts
index 3f4fb32511..52d925da82 100644
--- a/src/lib/db/feature-type-store.ts
+++ b/src/lib/db/feature-type-store.ts
@@ -69,12 +69,12 @@ class FeatureTypeStore implements IFeatureTypeStore {
     }
 
     async updateLifetime(
-        name: string,
+        id: string,
         newLifetimeDays: number | null,
     ): Promise<IFeatureType | undefined> {
         const [updatedType] = await this.db(TABLE)
             .update({ lifetime_days: newLifetimeDays })
-            .where({ name })
+            .where({ id })
             .returning(['*']);
 
         if (updatedType) {
diff --git a/src/lib/routes/admin-api/feature-type.ts b/src/lib/routes/admin-api/feature-type.ts
index 9ab4f19695..d4aff7d94f 100644
--- a/src/lib/routes/admin-api/feature-type.ts
+++ b/src/lib/routes/admin-api/feature-type.ts
@@ -13,13 +13,13 @@ import { createResponseSchema } from '../../openapi/util/create-response-schema'
 import Controller from '../controller';
 import {
     createRequestSchema,
+    featureTypeSchema,
     FeatureTypeSchema,
     getStandardResponses,
     UpdateFeatureTypeLifetimeSchema,
 } from '../../openapi';
 import { IAuthRequest } from '../unleash-types';
 import { IFlagResolver } from '../../types';
-import NotImplementedError from '../../error/not-implemented-error';
 
 const version = 1;
 
@@ -114,8 +114,16 @@ When a feature toggle type's expected lifetime is changed, this will also cause
         res: Response<FeatureTypeSchema>,
     ): Promise<void> {
         if (this.flagResolver.isEnabled('configurableFeatureTypeLifetimes')) {
-            throw new NotImplementedError(
-                "This operation isn't implemented yet",
+            const result = await this.featureTypeService.updateLifetime(
+                req.params.id.toLowerCase(),
+                req.body.lifetimeDays,
+            );
+
+            this.openApiService.respondWithValidation(
+                200,
+                res,
+                featureTypeSchema.$id,
+                result,
             );
         } else {
             res.status(409).end();
diff --git a/src/lib/services/feature-type-service.ts b/src/lib/services/feature-type-service.ts
index 39ac51d852..c31d222514 100644
--- a/src/lib/services/feature-type-service.ts
+++ b/src/lib/services/feature-type-service.ts
@@ -5,6 +5,7 @@ import {
     IFeatureType,
     IFeatureTypeStore,
 } from '../types/stores/feature-type-store';
+import NotFoundError from '../error/notfound-error';
 
 export default class FeatureTypeService {
     private featureTypeStore: IFeatureTypeStore;
@@ -22,6 +23,29 @@ export default class FeatureTypeService {
     async getAll(): Promise<IFeatureType[]> {
         return this.featureTypeStore.getAll();
     }
+
+    async updateLifetime(
+        id: string,
+        newLifetimeDays: number | null,
+    ): Promise<IFeatureType> {
+        // because our OpenAPI library does type coercion, any `null` values you
+        // pass in get converted to `0`.
+        const translatedLifetime =
+            newLifetimeDays === 0 ? null : newLifetimeDays;
+
+        const result = await this.featureTypeStore.updateLifetime(
+            id,
+            translatedLifetime,
+        );
+
+        if (!result) {
+            throw new NotFoundError(
+                `The feature type you tried to update ("${id}") does not exist.`,
+            );
+        }
+
+        return result;
+    }
 }
 
 module.exports = FeatureTypeService;
diff --git a/src/test/e2e/api/admin/feature-type.test.ts b/src/test/e2e/api/admin/feature-type.test.ts
index 4ceb529a9a..d1c78d9334 100644
--- a/src/test/e2e/api/admin/feature-type.test.ts
+++ b/src/test/e2e/api/admin/feature-type.test.ts
@@ -1,6 +1,6 @@
 import dbInit from '../../helpers/database-init';
 import getLogger from '../../../fixtures/no-logger';
-import { setupApp } from '../../helpers/test-helper';
+import { setupAppWithCustomConfig } from '../../helpers/test-helper';
 import { validateSchema } from '../../../../lib/openapi/validate';
 import { featureTypesSchema } from '../../../../lib/openapi/spec/feature-types-schema';
 
@@ -9,7 +9,14 @@ let db;
 
 beforeAll(async () => {
     db = await dbInit('feature_type_api_serial', getLogger);
-    app = await setupApp(db.stores);
+    app = await setupAppWithCustomConfig(db.stores, {
+        experimental: {
+            flags: {
+                configurableFeatureTypeLifetimes: true,
+                strictSchemaValidation: true,
+            },
+        },
+    });
 });
 
 afterAll(async () => {
@@ -32,3 +39,44 @@ test('Should get all defined feature types', async () => {
             ).toBeUndefined();
         });
 });
+
+describe('updating lifetimes', () => {
+    test.each([null, 5])(
+        'it updates to the lifetime correctly: `%s`',
+        async (lifetimeDays) => {
+            const { body } = await app.request
+                .put(`/api/admin/feature-types/release/lifetime`)
+                .send({ lifetimeDays })
+                .expect(200);
+
+            expect(body.lifetimeDays).toEqual(lifetimeDays);
+        },
+    );
+    test("if the feature type doesn't exist, you get a 404", async () => {
+        await app.request
+            .put(`/api/admin/feature-types/bogus-feature-type/lifetime`)
+            .send({ lifetimeDays: 45 })
+            .expect(404);
+    });
+
+    test('Setting lifetime to `null` is the same as setting it to `0`', async () => {
+        const setLifetime = async (lifetimeDays) => {
+            const { body } = await app.request
+                .put('/api/admin/feature-types/release/lifetime')
+                .send({ lifetimeDays })
+                .expect(200);
+            return body;
+        };
+
+        expect(await setLifetime(0)).toMatchObject(await setLifetime(null));
+    });
+    test('the :id parameter is not case sensitive', async () => {
+        const lifetimeDays = 45;
+        const { body } = await app.request
+            .put(`/api/admin/feature-types/kIlL-SwItCh/lifetime`)
+            .send({ lifetimeDays })
+            .expect(200);
+
+        expect(body.lifetimeDays).toEqual(lifetimeDays);
+    });
+});
diff --git a/src/test/e2e/stores/feature-type-store.e2e.test.ts b/src/test/e2e/stores/feature-type-store.e2e.test.ts
index bf90fcc6c8..8fe917ea6c 100644
--- a/src/test/e2e/stores/feature-type-store.e2e.test.ts
+++ b/src/test/e2e/stores/feature-type-store.e2e.test.ts
@@ -46,15 +46,13 @@ describe('update lifetimes', () => {
 
         for (const type of featureTypes) {
             const updated = await featureTypeStore.updateLifetime(
-                type.name,
+                type.id,
                 newLifetime,
             );
 
             expect(updated?.lifetimeDays).toBe(newLifetime);
 
-            expect(updated).toMatchObject(
-                await featureTypeStore.getByName(type.name),
-            );
+            expect(updated).toMatchObject(await featureTypeStore.get(type.id));
         }
     });