I've bought it on Google Play, but now I can't use it.
Every time I open the app, it says the trial is over, and I should buy the full version. But if I try to buy it again, Google Play will say that I've bought it so I can't buy it again.
So it kind of stuck on the strange loop: won't let me use because I'm detected not bought yet by the app, and won't let me buy because I've actually already bought it.