Short and sweet:

Is it possible to turn my 2 remaining months of Premium membership into 4 months of Gold membership? Does CHESScom do that sort of thing? Downgrades/upgrades?

~Dakota Clark

I'm pretty sure you can, go to the "Help & Support" link at the bottom of this page, click "Contact Us", and send a question to the membership and billing department.

yep. easy to downgrade. go to www.chess.com/membership.html and choose the plan you want. then you will see how much "credit" you have to apply. you can choose "gold monthly" and it will apply. 

that's what i thought, thx erik