Best to keep it simple. First, get a key storage cabinet big enough to hold every single key. Hopefully it will be expandable in case you need to add capacity later. Second, number every door. Get a floor plan of the building and... read more
You can have numbering system by which can differentiate by the letter, offices with O, workstations with W, Closets with C so that you can easily find it, then story wise, 1st story will be A, OA means offices in 1st Story , then third will come in sequence number or room wise also make it and mark them so you can easily identify them with this understandable naming or taging it.