I'll tell you everything you need to know about Flutter In App Purchase (Consumable & Non Consumable).
For Verifying the purchase, No third party is needed, Just Firebase and your Flutter App.
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Adding In App Purchase to a Flutter app requires correctly setting up the App and Play stores, verifying the purchase, and granting the necessary permissions.
In this course, you'll add two types of In App Purchase to an app and verify these purchases using Firebase.
The first purchase, "Get Premium" gives users premium access. This only has to be purchased once and is available forever. Such a purchase is non-consumable because the app cannot consume it but is valid forever.
The second option, "Get Game Coin" gives the user a direct benefit of 10 Gold Coins. These are directly available to the user and can be bought many times. This is called a consumable as it is directly consumed and can be consumed multiple times.
The backend service (provided for you) verifies the purchases using Cloud Functions and Firestore. Using Firebase makes the process easier, and in your production app, you can use this backend service. It's EASY | SECURE | RECOMMEND FOR PRODUCTION APP.