@Sal3488 It's up to you to set the parameters for guests' checkout procedure. You can use technical solutions like a doorbell camera or smart lock to observe whether guests seem to have departed, you can take a more hands-on approach by setting an appointment for checking them out in person, or you can designate a place for them to drop the keys on departure. Whatever works best for you, I suggest communicating with guests the day before departure reminding them of the checkout time and any tasks you require (e.g. key return, trash removal). An additional step could be sending you a message to alert you that they've left, but in my experience people really appreciate the most hassle-free checkout possible.