Accounting and billing for VPS hosting?

Question

Billing systems

Colleagues, good time!
Advise software or solution, please.
We develop the direction of VPS for rent in our company. Hypervisor and guest OS - Windows. There are several dozen physical servers and more than a hundred client virtual machines.
It is necessary to take into account in a convenient form, including:
on which server / node a particular VM is located;
parameters of each VM and history of their change;
the simplest billing for VM, based on the allocated resources;
accounting for used and free IP addresses, etc.

Answer 1

ISP system

Answer 2

Vmmanager ot ispmanager can do it all