You've obviously never stepped into a new situation at an existing shop. Stuff like that (including original installation media) gets lost all the time. That's simply the real world, and it's up to the inheritor of the situation to deal with it effectively amidst all the fires that crop-up to be stamped out, daily.
You must not have bothered to read the lines: But this software company said, " What Stan wanted from the card-processing software publisher was simple: an "unlock" key for the new installation. It's the kind of request software company customer service departments handle all day long. They check to make sure the caller has actually purchased the software in question, then email a new key or read it over the phone.
No, we can't give you a new registration for your old software. You need to upgrade to our latest version, and the upgrade will cost you [several thousand dollars]."; which adequately frames the position against proprietary software consumer-gouging.
An unlock key for the new installation would not necessarily have been identical to the earlier unlock key, used for the original installation. Again, a routine practice on the part of the vendors of proprietary software kludges.