@Dominik42
In the event of a catastrophic event like a Fire or life changing injury, who's insurance will cover it? I doubt your insurance company will and the fraudster that renting your apartment most certainly is not covered.
(There was a post recently, made by a rather naive young lady who sublet one of the rooms of her rented apartment and her Guest electronic goods were stolen and she could not afford to pay for them being “A Poor Student” … it makes me want to vomit.)
It is your duty to expel Him/her from your property and seek punitive damages (although you have little or no chance of getting anything)
This sort of activity is driving the cost of Airbnb rental down to ridicules levels and need to be sorted out.
Regards
Cormac
The Explorer’s Club Krakow III