There already exists a “Google Play licence check” permission apps can use to verify whether or not the app has been bought on a Google account that’s present on the device.
If people can crack the app to remove this (which is a thing for some of the popular apps), they’ll also figure out how to patch this out. This is strictly useful for free apps, and only serves to make it unviable to distribute verifiably clean apk’s outside of Google Play (so rip APKMirror)
Oh boy, does this also hold for people who don’t like any pets?