Version 5.x System Requirements
From WHMCS Documentation
WHMCS requires the following in order to run:
- PHP Version 4.2.x or later
- MySQL Version 3.2.x or later
- Curl Support (with SSL support)
- GD Image Library
- Ioncube Loaders Support
- Open_basedir Disabled (doable in the 'php.ini' - typically located in /etc/php.ini)
WHMCS does not need to be tied to a server for automatic account provisioning in order to function. You can use the system as a standalone billing & support center without any issues.