@Zacharias0
I think I mentioned this before in a prior post.......I state in my listing description and house rules that only for guests staying longer than 1 week, I will allow 1 load of laundry per week at no additional charge. I also explain that hosts handle laundry for towels and bedding so 1 load per week for personal clothes should be more than enough.
I also had problems with overuse with one guest in the past (for 4 months!) it was very frustrating when he would continue to do teeny tiny loads....whenever we brought it up he'd say sorry, I had nothing to wear, I ran out of socks, it won't happen again blah~blah~ over and over but of course it was pretty clear he had no intention of respecting the 1 load per week rule. Henry and I decided to just put up with it because although in terms of utilities and amenities he used more than our average guest, for the most part, he stayed out a lot only coming home to sleep and shower (and do laundry). We left an honest review with a thumbs down.
You did mention you will start locking the door to limit access so I think that will definitely help. Good luck~!