[dylan604]

I'd assume they would have a record of the user in their database. How else would they earn money from the data harvesting their app is a cover for? For the small number of apps that aren't solely data harvesting, surely they still have records of their users in a database as well? This question almost reads as if you're assuming the only record of an app would be through the store and not by the app developers themselves. I would find that truly shocking and quite comically sad if true.

It seems like it would be trivial for a user to login to the app acquired from a different store to be able to display a "welcome back" or even something along the lines of a "restore purchases" type of thing.

This can't be reinventing the wheel kind of a thing.

[scripturial]

In google play the purchaser information is mostly privatized and hidden from the developer. I assume Amazon is the same.

The only way a developer would know a person is an existing user is if they have a user sign up process inside the app itself.

[snotrockets]

Using android.content.SharedPreferences, set one singaling the user purchased a license from the Amazon copy of the app, read it from the Google Play app.

It is doable, the main issues is: 1. Getting users to redownload the app from the Play store 2. Maintaining this registration transfer mechanism

[axus]

I think issue #1 is a big one, how to download a paid app without paying for it? Not everything is freemium.

Shattered Pixel Dungeon was a good example of me paying on one platform, and then applying the upgrade to the free app after downloading on another.

[dylan604]

That's on the dev of the app. They should absolutely have the ability to see that you download the app, and allow full access again.

This isn't any different from a user switching to a new device and having to download apps again. Not everyone restores from backup and prefers clean installs. Downloading an app again should not be the point of friction