I'm not sure if iabu or not but this is an issue I have with my pil. They have a key to our house which DH gave them. They will ring the bell or knock when I'm there but will often drop in stuff or pick up stuff if I'm not there but usually will tell either me or DH they are dropping by. We came home from holiday recently (day time flight) to find some basic groceries left for us despite living 2 mins away from a shop and some tidying done and our post arranged. This doesn't bother DH but it bothers me as in makes me feel uncomfortable that that they let themselves into our home without asking/telling us. Mil can be quiet nosey which makes me feel uneasy about her being in our house. DH wouldn't even dream of asking for the key back and has stated that if my parents let themselves in and out he'd have no problem with it either. We changed the locks two years ago and mil kept going on about making sure she got a key from us.