So I suggest adding an option to them to either be able to terminate the existing locker, which dumps out all the item you have had in it and offers no refund. Or an option to re-key a locker, which will generate new code for an existing locker, for 200 chy or something like that. Saving on having to unload/load back the items into the locker.
This way if need to you can share locker code, without having it compromised for the duration and then having to rent a new one.