Nightfall trial key, any point?

I was going through my email archives and ran across an old one from the Nightfall release. It has a trial key that I never used. Would there be any point in adding it to my account now? I seem to recall that they used to open up another character slot or something so you could play with the new professions, but maybe that was only for pre-orders.

Mh yeah additional slot was for pre-orders.
You can try and use the key but I doubt it's even valid anymore...

Trial key will give you access to that game only for X hours playtime or Y days depending which comes first. If you don't have the game on your account it will work for the allotted time.
It is meant to be shared with friends or someone that wants to try out the game.

Yeah, if there's any friend you want to get hooked on the game, give the code to them