[kitsunesoba]

Practically speaking yes, and it’s probably ok to do that for personal use. Where things get shaky is if you want to use it professionally — even if you buy an old license key off of eBay Adobe could decide the license is no longer valid and sue you.

[prmoustache]

If you had already that license I don't think Adobe can revoke it. I don't think it is legal to revoke a license that is sold in the second hand market either.

The biggest risk I can think of is that the old product may be in some case vulnerable to compromised documents and by sharing the sandbox folder with your main computer you could in theory get the main machine compromised.