A rolling rental holds the future too

A storage unit under an active rolling rental is not available to anyone else, not only for the current month but for every future date.

The reason is that the renewal must have somewhere to go. If somebody booked the month after yours, your renewal would collide with them and you would lose the space to a calendar.

Anyone trying to book such a unit sees a message that the unit is under a rolling rental and is not available for that date.

The rule applies to a renewing rental that has not been stopped. One whose renewal was stopped releases the future, and the months after the end of the term become available again.