Some may know that you can check the WHMCS license of any company using WHMCS as their billing system by adding:

[precode]?licensedebug&forceremote[/precode] to any .php file in the whmcs folder.
Example:

[precode]announcements.php?licensedebug&forceremote[/precode]

If you run this, you will probably see information like

• licensekey
• licensetype
• Name of the licenseowner
• path to installation
• domain that are allowed to use this license

Not all are interested in showing this information and here is one way to hide it for the public.

Add this in your configuration.php:

[precode]
if(isset($_GET[‘licensedebug’])) {
unset($_GET[‘licensedebug’]);
exit(‘Contact support if you need to see this information’);
}
if(isset($_GET[‘forceremote’])) {
unset($_GET[‘forceremote’]);
exit(‘Contact support if you need to see this information’);
}
if(isset($_GET[‘revokelocal’])) {
unset($_GET[‘revokelocal’]);
exit(‘Contact support if you need to see this information’);
}
[/precode]

You can of course still verify that the domain are licensed to use WHMCS here.