sudden problem with activation

I have been playing the full version with the serial key I purchased a couple of weeks ago with no problems. Now suddenly it is requesting my serial key again. I entered it, it accepted it, and then then the same window continually reappears telling me to activate. I am no longer able to play my saved game because I am over the level limit for trial mode.

If anyone has any suggestions, I'd really appreciate it.

Any response to this?  I, too, continually get the Enter Your Key or Continue Playing in Trial Mode window.  I've owned this game for a couple years.

Download the latest version of the game from the TaleWorlds site, then install it and activate the game with your serial key. You shouldn't have this problem anymore.