Adding a free trial period to your app increases IAP conversion rates [0], but I've always found it a lot of work to implement a trial - once you're done developing the core of your app, you want to publish it as soon as possible, not spend 1+ days adding the code needed to implement a trial period. Using a low-tech solution like storing the installation date in the SharedPreferences works, but can be very easily circumvented even by non-technical users via uninstalling and reinstalling the app.<p>That's why I've developed a server-side solution that's very flexible (using offline grace periods, for example) and customizable - you can implement "try once per device" or "try once per Google account" trials, set custom trial periods, and even add multiple trials to a single app (one for each IAP, for example). I've decided to publish this as a library and open it up to everyone - you can check out the Android sample here [1].<p>Please let me know what you think and if there are any other features you'd like to see.<p>[0]: <a href="https://android-developers.googleblog.com/2016/11/learn-tips-from-memrise-to-increase-in-app-conversions-with-pricing-experiments.html" rel="nofollow">https://android-developers.googleblog.com/2016/11/learn-tips...</a><p>[1]: <a href="https://github.com/trialy/trialy-android-sample" rel="nofollow">https://github.com/trialy/trialy-android-sample</a>