Apple recently announced a "no-questions asked" 14-day refund on any app, music, book and film in the European Union, as part of an effort by the EU to clamp down on faulty digital goods.
The refund system allows users to get all of their money back in 5-7 days time, but the problem right now is users are still able to use the app after the refund. There is also no time-lock for refunds, meaning a user could complete a game in two weeks, and then ask for a refund.
An estimation of how many users typically ask for refunds tends to be low on mobile, but it is still a vulnerability for developers working on the Apps Store, allowing users to essentially never pay for goods.
Testing the system out, the refund process takes a few days and the app is removed from the 'Purchased' section on the Apps Store, however Apple does not remove the application from the user's iOS device.
The IPA file for the app can also be stored on a Mac, allowing the user to transfer the app onto various other iOS devices. Apple currently has no safeguards to stop this from happening.
Apple will most likely have a way of tracking abuse on the refund system, not allowing a certain number of refunds in a day or week. Apple may also ban users from asking for too many refunds, if they are found to be abusing the system.
It is unusual for Apple not to create barriers stopping users from getting an app for free, but the new refund system is still under work, and we would not be surprised to see a future update fix the current issue.