
Here is the simple way to have a differant room description and to fix your door/key problem.
Lets say you have the "Bedroom" and the "Closet." The closet is locked and you need a key to open it.
When your hero uses the key to unlock the door then turn on a flag (call it "keyuse" or something.
In the compass screen of "Bedroom" change the direction from "Closet" to "script." Edit the script and use a conditional. Make it so that if the flag "keyuse" is on then the player is moved to the closet. If the flag is off, then all you get is "Oh Darn, the door is locked."
When you use the "Closet Key" (either under the use command of the item, or in custom command setting) then you take the key from the player, type in something like "You turn the key and now the door is unlocked," and turn on the flag "keyuse."
Now when they go in the direction of the closet door they can get into the closet...everytime...forever.
Flags are your friend. You can use them to alter room descriptions as well.