Activate monster in other map when picking up item from a different map?

[SonOfLiberty796]

So my title might not make sense (lol) but ill explain here.

What I want to do is make a monster active when the player picks up a key. I know how to do that already, however, I want it to work when the player picks up the key from lets say Map 1. Then, Map 2's monster gets activated due to the player picking up the key from Map 1....is that possible? please help and thanks