I need to have a trial period (7 days) in my application. From this I came to know that you can do that by keeping permanent file, database or shared preference. Where do I keep that file so that the user isn't able to see/delete it. If I put that logic in Sharedpreference or a file with a path "data/data/packagename", when the application is uninstalled then all history will be lost. Any other workaround/ideas? Note: there is no server, application works locally with no Internet.