We have just implemented our new points reward system, you can get a premium upgrade by just doing add-ons reviews and/or uploading screenshots.
Points are earned by making add-ons ratings and quality reviews (not just "good" or "nice" kind of review), also when uploading screenshots (only approved pictures qualify). You earn 1 point for each add-ons valued and 2 points for each Screenshot uploaded, if your total points in the last 30 days reach 50, your account is automatically upgraded to Premium by 30 days.
When your earned upgrade expires our system will check again, if you have 50 point earned voila! another upgrade.
So keep rating add-ons and uploading screenshots.
To check your earned points or to redeem them, just visit your Account page.