Addon Modules Management
Addon modules allow you to create both admin pages and hooks to extend WHMCS further.
Modules can consist of just an admin page, or just hooks, or both. And they are all managed through the Setup > Addon Modules interface.
Once activated, the modules will display in a dedicated "Addons" dropdown menu within the admin area for quick & easy access from any page.
Management options consist of activating and deactivating of the modules, aswell as access control which allows full admins to define exactly which of the administrator roles are allowed to access each addon module.
We have a Video Tutorial demonstrating addon module management & access control @ http://www.whmcs.com/tutorials.php?i=addonmodules
Documentation for creating an addon module can be found at Addon Modules