This is something I have been noticing for the last year where I'll see it unlocked, lock it and the next day I'll come in and its unlocked again. This is a complaint I have raised as well. I have put up a clear sign that the door MUST be locked. People are using it as a regular exit instead of walking around and using the mud room.
Clear warning if you are reading this:
KRM regularly sells key controlled fire door alarms. The kind with the large red release paddle that set off an alarm when opened without a bypass key and will not turn off until someone comes with a key to turn it off.
For the convenience of *everyone*, do not tempt me to fund the purchase and installation of one, then give the keys to the board so they can open it whenever we need to move supplies in and out because technically that's a fire door. Don't ruin this for everyone else at the space.