I have built a free app and a paid app. When user upgrades or buys paid app, on its first launch, i want the app to send “unique id” to my server so that every time the app launches, it will check with server and authenticate to prove that the user actually paid for the app.
What I am wondering about is what I should use as “unique id.”
I am aware that there is android.telephony.TelephonyManager.getDeviceId() to get IMEI or MEID and use this to check the validity.
However, if I use this method, when user change the cellphone, then this would no longer work. Are there any way to get user’s google id that is connected with android market or some sort of unique id that is related to android market so that when user changes the phone, as long as the id to login to market is same, the app can authenticate?
Please look at the Android Licesing and Verification Libraray (LVL)
http://developer.android.com/guide/publishing/licensing.html