While there's very little we fellow users here on the forum can do to help with regarding a refusal by Adobe's servers to activate your license, it might be helpful if you'd define exactly what you mean by "not accepting license". It's possible you're having a basic installation problem, and not a problem with activation.
What error message do you get, when?
tech support was very little help
I'd like to make a public editorial comment on what seems like a bad recent trend...
Adobe really needs to continue to support the reactivation of prior versions!
Activation is not a feature that helps the customer, it's a feature that protects Adobe. It comes at an ongoing cost - both to the customer and to Adobe, and it's simply not acceptable for them to choose to stop paying that cost, and not allowing people to continue to use the software that they legitimately licensed.
Providing technical support for an older version is something that's completely different than providing activation support.
We fall a bit into gray area where someone has trouble installing an old version of Photoshop on a new computer, but if the problem is just that the user has exceeded the allotted activation count then there's no excuse for being put off by Adobe Customer Support. The activation technology is capable of continuing, as it has, to ensure the user isn't running the software on too many computers.
I really, really hope that I'm misinterpreting what sounds like a bad trend based on recent comments on this forum about Adobe Customer Support not supporting people in reactivating their older software after a failure or computer replacement.
With the Mac, it's a very bad idea to transfer Photoshop from backup. It breaks activation and results in a 150:30 error.
The best thing is to re-install using the original DVDs and the serial number. Then it can be activated.
If it does not accept the serial number, something is very wrong and requires a Customer Service call (they usually handle this). Usually that happens when the serial number is compromised and Adobe invalidates it. You'll need to have proof of purchase and I hope you registered Photoshop when you first installed it.
Noel, I know in the case of a HDD failure, it's not possible to deactivate, so as far as I know Customer Service does reset activations for CS3-CS6.