A storage company's month is occupancy and rent: filling units, taking reservations, and collecting the monthly payment without chasing. Management software starts exactly there, with online reservation by unit size and recurring billing — a customer reserves and pays from their phone, and the rent collects itself each month. Fewer empty units, no chasing overdue rent.
Occupancy is the only number that matters, and it moves for two reasons: someone who could not find the right size and left, and someone who has been paying for a unit they emptied months ago. Both are visible before they cost money, if the data is in one place.
Storage is a subscription with a physical lock on it. Reservation, standing payment, access code and the end-of-tenancy date belong to the same record, because when they live apart is when a unit sits empty without anyone noticing.