We provide a subscription to our app. Are there any standard technics to prevent users from duplicate installations in different devices?
2 Answers
In app payment requires that you let a user restore his purchases on a different device. I'm not aware of a standard way to verify that the previous devices content was removed.
If you're asking about just copying the files then there's storage encryption which you can read about here. Notice that it is breakable if someone tries.
You can collect device information from each device and then just compare if the new device is trying to install the app with the same account as in another device.
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