This key can be use on any door, doorframe, archway, or similar structure. Once the key is used, it will open to an empty apartment room that is 30ft x 30ft x 15ft. 

The interior of the apartment is warm and dry, regardless of the outside conditions. The empty contains a small bedroom, bathroom, kitchen, and living room that can be furnished however you want. 

Once inside the space, the attuned creature can close and lock the door, making it turn nearly invisible on the outside. A creature can make a DC 25 perception check to find it or they can see it if they have true sight. 

The space is perfectly livable and can hold up to three creatures. The creature attuned to this key can use their action to its command word, expelling all creatures from the space.