Apart from paying a standard (yet "to be determined") fee to play on this server, the subscription server's main difference will be the absence of an item shop and currency exchange. Everything on this server will be either quested, crafted, looted, or purchased with in-game currency. Players also won't be able to transfer a character (and its goods) from a F2P server to the subscription one.
The studio hopes to have the new server out around the time of the next expansion. It has committed to a subscription server for Europe, although it may nix the North American one due to lackluster interest from the community.