Android: Order ID of the purchased app
We plan to switch from a paid app to a free app when purchasing an app. We must provide any user who has paid for the application to receive a free in-app purchase for free.
I am thinking about the following solution. We will store a unique user ID (or unique order ID) on our servers. When we release a new free version of the app, we can check the unique user ID (or order ID) on our server. If there is a match, we get them for free in the app.
The question arises:
- If we receive the user's email, it will be too sensitive and the user may not want to give it.
- Can we get the App Order ID and check it against our Google Playlist of Order IDs?
- Any other unique user IDs we can use to verify that they bought the app before?
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Obtaining an email address will require you to modify the existing Paid Application. Also, it is not recommended for the above approach (+ cases where users have multiple accounts on the same phone and do not remember which mail is used will create more problems)
I would recommend using https://developer.android.com/guide/topics/manifest/manifest-element.html#uid
Android: sharedUserId
The name of the Linux user ID to be shared with other Applications. By default, Android assigns each app its own unique user ID. However, if this attribute is set to the same value for two or more applications, they will all have the same identifier - provided that they are also signed with the same certificate. An application with the same user ID can access other data and, if desired, run in the same process.
Determine the same userId via paid app and new free app with in-app purchases. Some data in paid applications can be used to identify a user without requesting any additional data from users.
Take a look at one of the solutions provided in this answer by user caw Suggesting additional media assets (graphics / sounds) as billed in Google Play app
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