Global Agenda will be free-to-play after purchasing. Hi-Rez Studios posted the announcement on their official forum today. Now the game's business model is more like Guild Wars, buying the game and its expansions but no subscription fee. You can access the entire announcement below.

Players can co-op with friends online, compete in fast-paced multiplayer matches, and conquer persistent territory with player-formed groups called agencies. The large summer expansion, titled Sandstorm, adds weapon variation and loot, new epic weapons across every class and a brand new Open Zone area complete with quests and new missions.

Try For Free – Players can download Global Agenda Credits and play until level 15 with no payment or credit card required.
Buy Once - A single purchase enables you to play forever. Progress thru 50 character levels, access hundreds of weapons, and experience all current content and gametypes on our worldwide, hosted servers with no subscription required.