Disclosed are methods of leasing or billing for the usage of a portable suction pump adapted for use in a suction-assisted would treatment system. The pump has means for recording time units corresponding to periods of time when the pump is operating and for providing reports of usage time. The pump further has means for detecting that the wound treatment system is operating normally so as to be compliant with standards for suction wound treatment, and for recording and reporting time of normal operation or compliant usage. The methods include leasing the pump at a payment schedule that is based upon the amount of actual usage time or the amount of compliant usage time. The lease payment may include an amount of pre-paid time units such that unused time units can be credited to a new or renewed lease for a replacement pump. The billing methods can also be based in whole or in part on a planned maintenance schedule for the pump.