Key Chain
Here is another thought.
When I was into manufacturing credit cards, we did a project for First Data Resources and Montgomery Ward. They were plastic key chains and they had a serial number on them.
When the person received the key chain, they entered their name and address information on a form and submitted it back to the recording agency.
Then, if the keys were lost and found by someone, they would put them into the mail box, postage prepaid and when the reporting agency received them, they would match up the serial number to the information received for that number and return them to the rightful owner.
Don't know if this is possible with these key chains, or, if AZ even wants to get in this type of operation, but, I just thought it might be a good idea.
Just some thoughts