Loss of Photoshop (and Lightroom) after computer reload

It seems unfair to prevent continued use of an old version in this way and at the same time block contact with a human being at Adobe help. Adobe's built-in product registration system  just does not allow for my previously acceptable and completely legal situation.

Does anyone have any suggestions or advice? I don't really need or want to pay a monthly subscription for something I already own and have previously been helped to continue using by Adobe.

It seems unfair because it is unfair. There is no technical reason why you cannot use the software you paid for, just a business decision by Adobe. It's true that the activation servers are no longer active, but Adobe have a version of the installer that does not require online activation. This used to be made available to licence holders via a website that asked for your original details, and would then issue a new licence key together with the activation-free installer. I believe that for a specific edition (e.g. CS3 Extended for Windows), everyone was given the same key and activation-free installer.

So, is there any way to obtain the installer and key today? As you've found, there appears to be no support route that will allow you to speak to anyone at Adobe who can help you, and the website was withdrawn several years ago (without warning). Whether (e.g.) a polite registered letter to Adobe's corporate address would receive a more productive response is unclear. If not, perhaps a more formal letter from your legal representative would be effective (Adobe will have something in the small print of the EULA saying they can do what they like, but this does not necessarily trump local consumer laws that may require them to give you access to the software you have paid to license). Whether you could obtain the activation-free installer and key via some unofficial route is another question, but you would need to be sure that it was coming from a trustworthy source, and know whether a licence holder may legally use an installer obtained in this way in your jurisdiction.

CS3, incidentally, will install and run even on Windows 11 if you have the activation-free installer, and in my limited testing Photoshop and Illustrator at least seem to be fast and stable. There are, of course, major unpatched security vulnerabilities in software of this age, so using it is not without risk. But whether this risk is justified should really be a decision for the user, not Adobe.

What Jane said, and more here:

https://community.adobe.com/t5/photoshop-ecosystem-discussions/locked-buying-used-photoshop-cs4/td-p/13267488