This is similar to the hack posted a few months ago about signing up with a new trial and then blocking certain addresses.
I haven't tried this yet, but I assume it works similar to using adb backup/restore with the app data saved...which is why it is a registered account. And when you run this with blocked address, it will remain as premium. You could transfer it to other devices with this method and the premium status still held....but this seems much much much easier.
I would block the address on your router because if DNS66 (or other app) fails, you'll lose premium and have to start over.
Curious to see how this holds up over time, but thanks for sharing!