I stayed in an AirBnB recently and the owner installed a smart lock while I was there. Assigning a unique code for each user is the entire point; you can invali

I stayed in an AirBnB recently and the owner installed a smart lock while I was there. Assigning a unique code for each user is the entire point; you can invalidate the code once their lease is up, rather than worrying about the keys getting returned or copied.