Variable Pricing for a Plan per Month

We offer variable pricing for our customers changing with revenue we created for our customers each month.

So our plan's for our customers is like: fixed + variable per month (we calculate variable part at the end of month)

how can we implement this variable structure with Zoho Subscriptions? Can we call an api to store variable part and Zoho Subscriptions use this value to invoice at the beginning of each month?

All suggestions and advice are welcomed