Access Smartphone Hardware Information

Hello.

I've been making an ios/android game for a while now. I'm tempted to try the business model of paying to unlock ingame content, which can be unlocked normally but optionally you can pay to unlock everything instantly.

Of course, I'm going to have to look into whether that's possible separately (although it'd be nice if anyone knew if that were at least possible in Unity), but my main concern is that if my only revenue source is from people paying to unlock the game, they could equally download a completed save file from the internet and everything would be unlocked.

So I'd like to know if there's some way to access some unique part of the hardware, a MAC address, IMEI number or anything, even if it's encrypted it'll do, and tie that to the save file. That way, if someone loads a save file that isn't tied to the phone, the save file data will immediately get erased.

Does anyone know whether that's possible, or if there's a more ideal solution?

Thanks a lot.