If you have entered your registration key, but are still in evaluation mode, there are two causes:
You will remain in evaluation mode if you have entered a license key, but this has not yet been activated.
If you go to the Product Registration window, this will show you that your key has not been activated.
Resolution: activate the license by clicking on the Activate Key button.
In this situation, you have entered with an Edition Upgrade or a Version Upgrade only.
An upgrade license cannot be used standalone, but must be used in conjunction with your original Standard or Extended Edition license. In other words you need to enter two license keys into AQT - both your Standard/Extended license plus the upgrade license.
Resolution: enter your original Standard/Extended license.