We have developed an application which we are selling on a per unit per week basis, and then billing every 4.3 weeks or every month. However, the amount of units a customer will be charged for may vary depending on customer usage per month. 

A unit in Zoho Creator will be one individual, so one month there will be records for 60 individuals, costing $1 by 60 by 4.3 weeks, so $258, while the next month the number of individuals may have increased to 70 or decreased to 50

Is it possible to have recurring subscriptions based on these parameters, reflecting number of individuals at the beginning of each billing cycle and then creating invoice accordingly?

Thanks,

Pat