Using items Options

[Noob_king]

How can I make certain objects respond only to certain items after you've selected them from the menu. For example, when you get a key all you have to do is walk towards the door and it will automatically open. How can I make it so you have to actually select the item from the menu before you can open the door. And have it so the key item will not do anything when you use it at any other time? Not only for keys but for items as well. Maybe certain npcs react differently when you go near them and select a certain item. I know how to do this by creating an event that turns on a switch that makes the item pull up a common event etc.... but then I have to make a new event to turn off the switch so the item doesnt do it all the time. I know there has to be an easier way. Thanks you in advance,