>the author is no longer with us
In german jurisdiction - and I'm sure in other countries, too - the posession will then go over to the heirs. Just because the spouse or other heirs don't know about the work it doesn't mean customers may take it as granted to own the software, the licenses continue, surely. But though by sense of justice the installation belongs to you, a lost activation key could be replaced by the heirs as goodwill only, not because you could demand the software to work on a new PC.
The situation is still not clear, whether you own the software as a whole, as it was contract work done for you, or whether it was just a customization or whether you just bought a license. Seeing a message in the software and your company name mentioned is judging a book by its cover.
As I do custom software for a living I know it is very inadequate to have an activation key with the setup. A company owning the software wouldn't put a lock on it, as they wouldn't sell it to competitors anyway, so it's still much more likely you bought a software maybe customized to your company, but still a work of a developer sold to many other morticians. With the argument the heirs don't know about the value of this software, could I claim a confectionery of a deceased owner, because I once baought a wedding cake there, made according to my ideas and with my name on it?
As you say you are a large mortuary business I also wonder, why you have problems with a single installation of a software. A software you obvisouly did install long ago and didn't care to store it's activation code. All this does point to being a usage license owner only. Besides not naming the product.
No matter what I or others here personally think about this, it's not a thing you can get solved by a Foxpro developer, just because it's Foxpro software. Without source code, we can also only try to decompile the installed EXE and/or DLLs, and that also won't put you in a position to maintain and expand that software for future needs. A decompilation has no documentation, mostly not even comments in sources. It's hardly possible to do more than recreate an EXE from the decompiled product. Without knowing it, as the developer did. So think about that: Just solving your current installation problem doesn't solve all future problems you might have, even if you say this software works stable for you without support.
I'd say fate has decided for you, to find a new route, a new software. Something maintained by a living developer or better yet a company having interest of continuous development of the product. The situation would differ much, if the sources were available. You have the best chances to negotiate with heirs to get the sources, maybe even for free, when they don't have an interest in continuing the business around that and/or other products of the developer. And then you are in a much better position also in regard of maintaining that software and adopting it to future needs or migrate to another basis of a not deprecated programming language.
Bye, Olaf.