Is it legal to sell on CS3 (design premium) software?

Richardnwhite wrote: It has been properly deactivated from my Mac. I bought it in 2009 and have just upgraded to CS6.

All depends on how you upgraded.

1) if you had a full version of CS3 then bought a perpetual license upgrade (box shipped to you or downloaded) to CS6 then you're still using the same CS3 license (CS3 full version serial number with a CS6 upgrade serial number) so you cannot sell CS3.

2) if you had a full version of CS3 then bought a full version of CS6 then you're free to sell your CS3 license.

Follow these steps to transfer the license http://helpx.adobe.com/x-productkb/policy-pricing/transfer-product-license.html

3) if you had a full version of CS3 then joined the Cloud to get CS6 then you're free to sell your CS3 license.

Follow these steps to transfer the license http://helpx.adobe.com/x-productkb/policy-pricing/transfer-product-license.html

Richard,

To elaborate a little on what John said:

It is illegal if it has ever been used as a basis for any upgrade at a reduced price, legal if it has never been used in that way.

>upgraded to CS6

You may NOT sell a product that was used as the serial number basis for a reduced price upgrade