diff --git a/src/lib/openapi/index.ts b/src/lib/openapi/index.ts
index 9772f3849b..59b07cf92a 100644
--- a/src/lib/openapi/index.ts
+++ b/src/lib/openapi/index.ts
@@ -133,6 +133,7 @@ import {
     upsertSegmentSchema,
     createStrategySchema,
     updateStrategySchema,
+    updateFeatureTypeLifetimeSchema,
     userSchema,
     usersGroupsBaseSchema,
     usersSchema,
@@ -337,6 +338,7 @@ export const schemas: UnleashSchemas = {
     upsertSegmentSchema,
     createStrategySchema,
     updateStrategySchema,
+    updateFeatureTypeLifetimeSchema,
     userSchema,
     createUserResponseSchema,
     usersGroupsBaseSchema,
diff --git a/src/lib/openapi/spec/index.ts b/src/lib/openapi/spec/index.ts
index d20a8acf8b..f7fce2c17a 100644
--- a/src/lib/openapi/spec/index.ts
+++ b/src/lib/openapi/spec/index.ts
@@ -150,3 +150,4 @@ export * from './telemetry-settings-schema';
 export * from './create-strategy-variant-schema';
 export * from './strategy-variant-schema';
 export * from './client-segment-schema';
+export * from './update-feature-type-lifetime-schema';
diff --git a/src/lib/openapi/spec/update-feature-type-lifetime-schema.ts b/src/lib/openapi/spec/update-feature-type-lifetime-schema.ts
new file mode 100644
index 0000000000..fef35dbda4
--- /dev/null
+++ b/src/lib/openapi/spec/update-feature-type-lifetime-schema.ts
@@ -0,0 +1,25 @@
+import { FromSchema } from 'json-schema-to-ts';
+
+export const updateFeatureTypeLifetimeSchema = {
+    $id: '#/components/schemas/updateFeatureTypeLifetimeSchema',
+    type: 'object',
+    required: ['lifetimeDays'],
+    description:
+        'Data used when updating the lifetime of a [feature toggle type](https://docs.getunleash.io/reference/feature-toggle-types).',
+    properties: {
+        lifetimeDays: {
+            description:
+                'The new lifetime (in days) that you want to assign to the feature toggle type. If the value is `null` or `0`, then the feature toggles of that type will never be marked as potentially stale. Otherwise, they will be considered potentially stale after the number of days indicated by this property.',
+            example: 7,
+            type: 'integer',
+            nullable: true,
+            minimum: 0,
+            maximum: 2147483647, // Postgres' max integer: https://www.postgresql.org/docs/9.1/datatype-numeric.html
+        },
+    },
+    components: {},
+} as const;
+
+export type UpdateFeatureTypeLifetimeSchema = FromSchema<
+    typeof updateFeatureTypeLifetimeSchema
+>;
diff --git a/src/lib/routes/admin-api/feature-type.ts b/src/lib/routes/admin-api/feature-type.ts
index 97e518d32b..9ab4f19695 100644
--- a/src/lib/routes/admin-api/feature-type.ts
+++ b/src/lib/routes/admin-api/feature-type.ts
@@ -4,11 +4,22 @@ import FeatureTypeService from '../../services/feature-type-service';
 import { Logger } from '../../logger';
 import { IUnleashConfig } from '../../types/option';
 import { OpenApiService } from '../../services/openapi-service';
-import { NONE } from '../../types/permissions';
-import { FeatureTypesSchema } from '../../openapi/spec/feature-types-schema';
+import { ADMIN, NONE } from '../../types/permissions';
+import {
+    featureTypesSchema,
+    FeatureTypesSchema,
+} from '../../openapi/spec/feature-types-schema';
 import { createResponseSchema } from '../../openapi/util/create-response-schema';
 import Controller from '../controller';
-import { getStandardResponses } from '../../openapi';
+import {
+    createRequestSchema,
+    FeatureTypeSchema,
+    getStandardResponses,
+    UpdateFeatureTypeLifetimeSchema,
+} from '../../openapi';
+import { IAuthRequest } from '../unleash-types';
+import { IFlagResolver } from '../../types';
+import NotImplementedError from '../../error/not-implemented-error';
 
 const version = 1;
 
@@ -19,6 +30,8 @@ export class FeatureTypeController extends Controller {
 
     private logger: Logger;
 
+    private flagResolver: IFlagResolver;
+
     constructor(
         config: IUnleashConfig,
         {
@@ -29,6 +42,7 @@ export class FeatureTypeController extends Controller {
         super(config);
         this.featureTypeService = featureTypeService;
         this.openApiService = openApiService;
+        this.flagResolver = config.flagResolver;
         this.logger = config.getLogger('/admin-api/feature-type.js');
 
         this.route({
@@ -50,15 +64,61 @@ export class FeatureTypeController extends Controller {
                 }),
             ],
         });
+
+        this.route({
+            method: 'put',
+            path: '/:id/lifetime',
+            handler: this.updateLifetime,
+            permission: ADMIN,
+            middleware: [
+                openApiService.validPath({
+                    tags: ['Unstable'],
+                    operationId: 'updateFeatureTypeLifetime',
+                    summary: 'Update feature type lifetime',
+                    description: `Updates the lifetime configuration for the specified [feature toggle type](https://docs.getunleash.io/reference/feature-toggle-types). The expected lifetime is an integer representing the number of days before Unleash marks a feature toggle of that type as potentially stale. If set to \`null\` or \`0\`, then feature toggles of that particular type will never be marked as potentially stale.
+
+When a feature toggle type's expected lifetime is changed, this will also cause any feature toggles of this type to be reevaluated for potential staleness.`,
+                    responses: {
+                        200: createResponseSchema('featureTypeSchema'),
+                        ...getStandardResponses(400, 401, 403, 404, 409, 415),
+                    },
+                    requestBody: createRequestSchema(
+                        'updateFeatureTypeLifetimeSchema',
+                    ),
+                }),
+            ],
+        });
     }
 
     async getAllFeatureTypes(
         req: Request,
         res: Response<FeatureTypesSchema>,
     ): Promise<void> {
-        res.json({
-            version,
-            types: await this.featureTypeService.getAll(),
-        });
+        this.openApiService.respondWithValidation(
+            200,
+            res,
+            featureTypesSchema.$id,
+            {
+                version,
+                types: await this.featureTypeService.getAll(),
+            },
+        );
+    }
+
+    async updateLifetime(
+        req: IAuthRequest<
+            { id: string },
+            unknown,
+            UpdateFeatureTypeLifetimeSchema
+        >,
+        res: Response<FeatureTypeSchema>,
+    ): Promise<void> {
+        if (this.flagResolver.isEnabled('configurableFeatureTypeLifetimes')) {
+            throw new NotImplementedError(
+                "This operation isn't implemented yet",
+            );
+        } else {
+            res.status(409).end();
+        }
     }
 }