Unless you get crafty, machine identifiers aren't stable on Windows and will change with updates. So if you update windows and reinstall an app, a lot of naive

Unless you get crafty, machine identifiers aren't stable on Windows and will change with updates. So if you update windows and reinstall an app, a lot of naive software will detect that as a fresh install on a fresh machine. That would really suck for a small Unity dev to get screwed by a Windows update that forces reinstall of their users' game libraries - which isn't that uncommon.