My current Flutter app already runs smoothly with a free membership tier. I now want to introduce a paid premium membership that users can purchase through native in-app purchases on both iOS and Android. Scope of the upgrade • Integrate Google Play Billing and Apple In-App Purchases into the existing codebase, wiring everything through one clean, reusable service class. • Create purchase flow UI—upgrade button, confirmation screens, and graceful failure handling—aligned with my present design language. • Persist purchase status locally and remotely (I already store user data; you can tap into the same backend endpoint) so that membership survives reinstalls, logouts, and multiple devices. • Unlock premium privileges the moment the transaction is acknowledged: – Ability to upload additional pictures on listings – Option to mark ads as “Featured” – Preferred placement for those ads in search and browse results • Gate the above features for free users while keeping all existing free functionality intact. • Add a simple “Manage Subscription” page that lets members restore purchases or downgrade. Acceptance criteria 1. A test account can complete a sandbox purchase on both platforms and immediately see more-picture upload limits, featured ad toggle, and preferred placement take effect. 2. Cancelling or expiring the subscription reverts the account to free limits within 24 hours. 3. No regression bugs appear in the current free workflow. The project is self-contained: I provide the full repo, existing backend endpoints, and the premium icons/assets. Bring your Flutter, Dart, and native store billing know-how, and let’s make this upgrade seamless for my users.