If your organization has lots of keys to manage, let us help you manage them!
Add a key as a suggested resource to any room setup where the key would apply, so the owner remembers to request a key.
The owner can request more than one key and add a note about who else will need an additional key.
Once the event is approved, the Approvers can leave a note in the Event Activity showing when they gave the key to the Owner and when they received it back.
As people need to check out keys, add the appropriate key to the event to track where the key was last and ensure it is returned at the end of the event.