How to track how much time an app is installed on a single device

Question

How do I track how long an application has been installed on a device?

If i use a shared preference, the data is cleared. Any ideas?

Answer 1

On each end every initial (first) launch of the application you can send a call to a server (your one) with the IMEI of the device and save that in a database or something else. Each time you receive the same IMEI just increase the total counts.

Here you can see what exactly is the IMEI

Here you can see how to get the IMEI of the devices you are currently interested in. (Check the accepted answer)