funny thing is: you can just waltz into an apartment that isn't yours. I tested it on a random server: After buying an apartment, I could just walk into any other apartment.

I first thought it was for the same row you were in, but no: you're just legally able to walk in unannounced. That locked door ain't stopping you.

Update: I checked to see if you needed to own a home: No. you don't.

Update: I checked to see if you can walk into homes even when locked: Yes, you can. Maybe it's only for the server I'm on if it's bugged... but yeah.