As I understand it, the SU variant of the software is what's installed when you download from this page:

http://www.intersystems.com/library/software-downloads/

And as your error message states, this variant is barred from using a cache.key file to unlock further features.

I think you'll need a different software kit. AFAIK you'll be able to "upgrade" your current SU installation in situ without losing anything (provided you've followed the rules about how to name any of your own code that you store in %SYS).

Those of us with support accounts can download software kits via WRC Direct. But assuming you don't have such an account yet, the InterSystems folk who provided you with the evaluation key are probably the best ones to ask about how to get hold of the software kit you need.

Have you considered implementing a Caché source code management tool such as Deltanji from George James Software, for whom I work? A Deltanji workflow can propagate code from one namespace to another, and can also propagate deletions. In other words, if you decommission a class in DEV, then propagate the now-decommissioned code object to TEST, the class will be deleted from TEST.