Offhand, I don't recall the thread his comment was in, but UPMan addressed this at least once before. That if a scanner, sent in for repair, got a board replacement, but the person that sent it in did not have the keys (in other words, was not the original purchaser), that the repair department could contact him to generate new keys for that scanner. That's why I suggested including a note. Of course, if the main board was not replaced, then keys would not need to be re-entered. But if that was the case (board replacement), then a 'heads up' note would be a prudent precaution.
My understanding is that if the scanner is re-registered, that does not pull up any previous upgrade purchases. If that is incorrect, then hopefully Uniden Support or UPMan (if he has time to see it before his upcoming hospital stay) will provide corrected information.