Works great! For those saying they want to buy keys: you will have to sign in with your Facebook account, uninstall the modded version, install the official version of the app. Once you started up the official version, log into Facebook again, then buy they keys. Now uninstall the official version and reinstall the modded version and sign in again, it will synch your game so now you have access to the keys.
It's a little convoluted, but I think it's the easiest solution.
And thanks to the modder of course!