WHM CompleteSolution (WHMCS) is a Client Management, Billing & Support System designed for cPanel and WHM Web Hosts. Integrated directly with the WHM and cPanel server management software, WHMCS can provide your hosting company with high levels of automation and drastically reduce the time you spend administering simple tasks.
Including automatic invoice generation, support ticket system, affliate system, and much more! For more information and a full feature list click here.
It auto-creates accounts on WHM servers. You can set it to:
Automatically create the account as soon as an order is placed
Automatically create the account as soon as the first payment is received
Automatically create the account when you manually accept a pending order
Do not automatically setup this account