Flutter App: Implement Monthly Subscription Payments and Premium Content Access

We are seeking an experienced Flutter developer to integrate a comprehensive subscription payment flow into an existing Flutter application. The primary goal is to enable users to subscribe to a monthly plan, granting them access to exclusive premium content within the app. The project requires the implementation of core subscription functionalities, including a basic flow for canceling and restoring subscriptions. The focus of this task is strictly on the payment and subscription logic; no other development work is required. The successful freelancer will be provided with the current project files and a detailed screen flow to guide the implementation. Prior experience with in-app purchases on both Android and iOS platforms, as well as familiarity with RevenueCat, will be a significant advantage.