android trial licensing

I would like to give trial of the app for some time.on expiry of this time, the app shouldn't' start.

You can't stop it from starting, but you can close it immediately on it's start after checking.

If a user installs the trail version for the second time, the app should be able to detect it and refuse.

Store device details on a server, and check with the server if a trial was previously done on this device. Use IMEI or MAC addresses to distinguish devices. Remember to disclose to the user that you're taking those addresses from them.

The app should detect if the user tries to modify the dates inorder to extend the trial period.

Use encryption/checksums on your files. If you can't decrypt the data to an expected format, or the checksum fails, your files were modified.

On launch of the app, it should check whether it is installed from authorised source like googleplay.... or side loaded.

Use LVL.

Source: http://stackoverflow.com/questions/12552527/android-trial-licensing

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