My Android game on loads of pirate sites...

Is there any way to prevent the Android game being copied and placed on pirate sites or at least make it more difficult to do so?

My game is on Google Play and now has 153K downloads and about 9K regular users. I guess this attracts pirates. I'm not overly worried but it irritates me and there ought to be a way to prevent it.

Any suggestions would be much appreciated.

Quote from janpier

I don't think it's a problem, as advertising and in-app purchases almost certainly have the same code, so the revenue goes to the developer. moreover it also has more visibility, the only gain for those who manage these sites is in the advertising of the site and that's it

Thank you janpier I will stop worrying about it for now.

Quote from NaitorStudios

Well, from what I know, the only way people avoided being pirated is by only unlocking the full game with in-app purchases...
There are other ways, like checking online, but seems complicated and it may be a problem for offline users.

Thank you NaitorStudios, I agree with not doing a check online and an overall hassel. Most of my users are young, horse crazy girls and I think they will mostly use Google Play to download games.