The licensing tools for Houdini are:

hkey: A graphical licensing tool for managing licenses. Also known as License Administrator.
sesictrl: The non-graphical "hkey". Use this to perform license operations in the terminal shell.
sesinetd: The license server daemon/service.
hserver: The client helper program that acquires licenses by communicating with sesinetd.

The location of licensing tools:

Windows
Prior to H19

• hkey, sesictrl: C:\Program Files\Side Effects Software\Houdini 18.0.xxx\bin
  
• sesinetd, hserver: C:\Windows\system32
  

From H19

• hkey: C:\Program Files\Side Effects Software\Houdini 19.0.xxx\bin
  
• hserver: C:\Program Files\Side Effects Software\Houdini Server
  
• sesinetd, sesictrl: C:\Program Files\Side Effects Software\License Server
  sesinetd.options needs to be set in this directory.

Linux

• hkey, hserver: /opt/hfs19.0.xxx/bin
  
• sesinetd, sesictrl: /opt/hfs19.0.xxx/houdini/sbin
  

Mac:

• hkey, hserver: /Applications/Houdini/Houdini19.0.xxx/Frameworks/Houdini.framework/Versions/Current/Resources/bin
  
• sesinetd, sesictrl: /Applications/Houdini/Houdini19.0.xxx/Frameworks/Houdini.framework/Versions/Current/Resources/houdini/sbin
  

The License Administrator (hkey) is the easiest way to install or manage Houdini licenses.