@Retune,
#1 PS 7.0 predates CS2 which means it won't run right on modern equipment. This isn't just about which OS you have. It's about the scratch disk which is something else. Photoshop 7.0 cannot see drives bigger than 1TB. Such a disk will be invisible to PS 7.0 so you will receive error reports that no scratch disk is available. Anyone who is familiar with Photoshop knows that available scratch disk is essential for using the software.
#2 Adobe doesn't accept transfer of license requests unless BOTH parties -- the current owner (seller) and new owner (buyer) -- submit a written request. And the seller must prove they have a registered, legitimate serial number that is neither an educational nor volume licensed edition. Good luck with that.
"Copies of Photoshop 7.0 have recently sold on ebay.co.uk for £227 and £272"
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#3 You can believe whatever preposterous Internet claims that you care to believe but that doesn't make it true. For software, eBay is a pirate's den of scammers & thieves who will say and do just about anything to extract money from people. Scammers who enlist cohorts to up-bid on auctions is nothing new BTW ;-).
Real people of sound mind do NOT pay more than 5 Euros for 15 year/outdated software. Not when they can outright purchase new & supported software like PS Elements -- which does more than PS7 ever did -- for less than $100 Euros.
https://www.adobe.com/products/photoshop-elements.html
Or they can lease the Photography Plan for about $120 euros per year.
https://www.adobe.com/creativecloud/photography.html
There's just no upside to buying or selling outdated software on auction sites. In the end, the seller ends up paying more in listing fees and other nonsense than they actually make on the sale. And buyers put themselves at huge risk for cracked software that's potentially infected with malware or ransomeware. Sorry but it's just not worth it for either side.
Goodbye & stay safe everyone! 🙂