The license server is called sesinetd.

You must have "admin" rights (root, sudo) to be able to stop/start the license server.

Windows

You can start and stop the HoudiniLicenseServer in the Services area of Windows.

1. Control Panel -> Administrative Tools -> Services
2. The service HoudiniLicenseServer controls the license server program sesinetd.

Linux

1. Usage: /etc/init.d/sesinetd {start|stop}

Mac

1. Launch the Terminal from Utilities
   
2. To stop the license server: sudo launchctl unload /Library/LaunchDaemons/com.sidefx.sesinetd.plist
3. To start the license server: sudo launchctl load -w /Library/LaunchDaemons/com.sidefx.sesinetd.plist

If you receive an error saying /Library/LaunchDaemons/com.sidefx.sesinetd.plist: No such file or directory, please reinstall Houdini and choose Commercial Licensing. This will install the necessary license server files.

When you restart the license server software on a centralized server machine, the remote clients will not lose their sessions for approximately 5 minutes of a failed heartbeat (or license check).