Must one pay a full month's rent for an 11-day stay in a shared apartment after the contract has expired?

The tenant must pay 11 days' worth of the month's rent, unless there is a condition or custom to the contrary. If the contract stipulates, or custom dictates, that whoever occupies the property for a few days of the month is liable for the entire month's rent, then the tenant is obliged to pay the full month's rent, and he has the right to utilize the house for the remainder of the month.