A lease is a commitment that bills itself over time
The signature is the start, not the transaction. What follows is a schedule: rent at an agreed frequency, escalation at agreed points, service charges that may recur on a different cycle, and an end date that triggers renewal or handback. Modeling the lease as a recurring commitment rather than a stack of manual invoices is what stops billing depending on somebody remembering.
Unit availability is the number the whole business asks for
Which units are vacant, which are reserved, which are occupied and when they free up. That question is asked by leasing, finance and management with different intentions, and it is only answerable in one place if the unit is a real record carrying its own status and history rather than a row in a leasing spreadsheet.
Service charges and collections behave differently from rent
Service charges often recur on their own cycle, sometimes reconcile to actual cost at year end, and are frequently disputed separately from rent. Keeping them as their own billing stream against the same unit and tenant means a dispute over one does not hold up collection of the other.
