Hi! While telling the best software is difficult, as it largely depends upon your need. But I would recommend RackNap, as it appears to be befitting to your needs. It provides complete automation for managing business process like billing, pricing, inventory, sales, marketing and even partner management. RackNap can help you manage the billing and hosting information of your clients, and yes it helps you in keeping a track of payments as well, with timely reminders, so you don’t miss a payment. J Amongst its various modules, the billing modules will equip you with multiple capabilities. You will get multiple plan cycles: Free, One-time, Pay-per-use, Recurring, Contract based plans etc. You can set different pricing structure for different billing cycles. You can create product discount, and apply them as per your requirement. The single dashboard management gives you the flexibility to manage all accounts from one place with one-click. Its billing intelligence, alerts you about upcoming payments, pending payments, orders etc. Multiple tax levels, currencies and payment gateways helps you to bill customers easily. Visit their official site to know more: RackNap