Flutter Developer – iOS & Android Subscription / In-App Purchase Integration

I have an existing Flutter/Firebase mobile application that is complete and being prepared for launch on the Apple App Store and Google Play Store. I need an experienced Flutter developer to implement the app's subscription/payment infrastructure on both platforms. Required work: Implement monthly and annual auto-renewing subscriptions for iOS and Android Implement a configurable free trial Integrate with Apple App Store and Google Play subscription systems Add subscription/paywall and entitlement logic Handle active, trial, canceled, expired, and failed-payment/grace-period states Implement Restore Purchases Ensure subscriptions are recognized appropriately across supported devices/accounts Add a Manage Subscription option directing users to Apple/Google subscription management Ensure pricing and free-trial settings can be changed through App Store Connect and Google Play Console without requiring an app update or developer changes for normal pricing adjustments Do not hard-code subscription prices in the app; display applicable store pricing Track trial starts, paid conversions, cancellations, and expirations in analytics Test the complete purchase flow on both iOS and Android Submit/update the production builds in both stores Required experience: Flutter/Dart, Firebase, Apple StoreKit/App Store Connect, Google Play Billing/Play Console, mobile subscription entitlement management, and previous production subscription implementations. Please provide examples of Flutter apps where you personally implemented subscriptions on both Apple and Google, explain the subscription architecture you used, and provide your fixed-price quote and estimated completion time.