I'm pretty sure I'm past that part now since I remember getting that key at the start. I'm at the lab part, and the only place that I can't get into is a room with a sign that says " Director's Office, " and then there are also the asylum looking rooms that are all locked. I'm just not sure if I'm missing something or if this is where the game is up to so far in development.
edit: apologies, I just went from the beginning and read the note at the start again and it said the lab area was still being worked on.