I have a developer license key for GF all registered and working perfectly.
I have installed the AWeber Add-On and it's asking for me to 'register your copy of Gravity Forms'.
No matter how many times I add the license (and get a green tick) each time I go back to the plugins page it's asking, again, to register.
The add-on itself works perfectly, apart from asking to register and GF itself accepts the license.