http://support.chess.com/Knowledgebase/Article/View/182/19/does-chesscom-offer-benefits-for-elite-or-titled-players
NM

I'm not quite sure what proof you have to send them, but you get a free premium membership from them!
[EDIT]: Scottrf beat me.

Here you go:
- digital image of government document (drivers license, etc)
- image of your FIDE certificate or other official chess document
- link to a post on your website/blog, etc (me - how does this prove anything? I'm IM Silman and here's a link to my blog - NOT)
- your ICC or PlayChess username/handle (send us your username/handle and we will message you)
I'm an NM. What do I have to do to have that label added to my account?