How to make demo version of application

[Pramod P Deore]

Hi, I had make one application for android, But now I want to make a trial version of that application. The trial application is valid for only 15 days. Once user use that application will not allowed to used for second time. I had tried it by storing IMEI number in file , but my problem is that if I create a file inside the application then when application is uninstall file is also deleted and I don't want to create a file on SDCard. Suppose client does not have GPRS active so I can't store the IMEI number on server.
As I know we can't create a file outside the application (except SD card), so how could I maintain the record of IMEI number so user can't use the trial version of that application more than once.

Thanks in advance

[Ulf Dittmer]

I wouldn't worry about people who uninstall and then reinstall applications to avoid hitting the demo limitations after N days. Folks who are prepared to go to that length to avoid paying a few bucks very likely would never pay - hence no lost sale for you.

What's more, you actually want to allow people to try an application again. For starters, they might run it once to see how it looks and then forget it about -later, when they rediscover it, the period would be over forever - not good. Or they might not like version 1.0, but want to try it again once 1.4 comes out which has the feature they really missed in 1.0.

For all these reasons you should allow people to re-try an app if they reinstall it.