Or they could sell a service to manage the device keys. The could even bundle it for free. They might even give it a terrible, anti-descriptive name like “find my”
Find My Feature from apple.com:
> Activation Lock is designed to prevent anyone else from using or selling your device. When you enable Find My on your device, Activation Lock is turned on automatically.
> Your Apple ID and password will then be required in order to erase or reactivate it. And if someone is able to erase your device, the Hello screen will show that it’s locked, locatable, and still belongs to you.