The Registry path that contains entries for the Advanced Server Alerter service is as follows:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\AdvancedServer\AlertParameters
AlertAdminOnLicenseOverflow REG_DWORD 0 or 1
Specifies whether the server sends an administrative alert message when the maximum allowable number of clients is exceeded.
Default: 0 (message will not be sent)
You can change the value of this key using the AS/U Administrator.
AlertUserOnLicenseOverflow REG_DWORD 0 or 1
Specifies whether the server sends a message to a client that tried to link but failed when the maximum allowable number of clients was exceeded.
Default: 0 (message will not be sent)
You can change the value of this key using the AS/U Administrator.