346464 Usage Based Billing Solution

I need a system similar to google Adwords billing setup or any utility company. The system must: Process transactions through [login to view URL] or similar merchant service. Auto-charge customers monthly based on usage(ie variable amounts). For example: A customer signed up and agrees to pay $5 per lead, in the previous month they received 10 leads, the system needs to charge the customer $50 automatically. Same deal if the next month they get 100 leads, they need to be charged $100 the next month without any action of their own. Let me know my options – Ideally the customer credit card information is NOT stored on my servers but a commercial billing software of some sort with an API that can work in sync with my company. Let me know my options in the PMB, comments like “can get it done” will just cause your bid to be removed. Elaborate your solution and costs, I don't mind paying for a expensive software in addition to hiring you to implement it.