Yes, it is due to your trial account. Those are limited to level 14.
Might want to give this a read.
http://wiki.cohtitan.com/wiki/Trial_Accounts
If you aren't ready yet to buy the game, you can still make other characters to play... but c'mon. You know you want to buy it. 
Welcome to the game!
Here's to hoping you stick around, it's a great game and there are a lot of great players out there looking for someone new to join their teams.
Hello guys, new to game on trial program and I hit 14 got fast flight and Im loving the game but I cant get any more xp? is it because im on the trial? thanks Just curious whats goin on