Creating a trial app with a feature that expires after being used twice

You cannot achieve this with the built-in trial mode.  It is based entirely on the time limit you choose when publishing the app.  After the time limit is up, the app will stop functioning.

To do what you want to do, you will have to write your own code.  One of my apps, a word processor for example, lets the user use the app with full features for 7 days.  After 7 days, instead of stop opening, it simply goes into read-only mode until the user buys it.  The advantage of doing it this way instead of making the app non-functioning forever after 7 days is the user will always have the opportunity to see what's new in my future updates.  I don't want to lose potential customers!  Nothing the user can do to reset the 7 days trial. They can uninstall and reinstall as many times as they want.  They can delete the settings file all they want.  My method doesn't require the app to check over the internet.  I'm sure if you think hard enough you will figure out a way like I did.  I'm just letting you know that there is a way and it is possible.  I just don't want this method to be known too widely.

Are you saying your method is different from the 'Expiring Product' option I mentioned? To me it sounds the same as that