I dropped the MPEG2 (Mainconcept MPEG-2) DVD ready files to DVDA7, and after being put there, the activation dialog box popped up. That's what I experienced previously.
I just tried with avc Blu-ray ready format, and found no activation requred.
Share my pic on how to show the Track Level buttons in VP15, in case you need to make more FAQ point specifically for this. Some users may get confused on how to turn it on.