Greetings all.
I downloaded houdini-14.0.201.13-macosx_x86_64_clang5.1_10.9.dmg with the intent of using the FREE restricted version, Houdini Apprentice. I never attempted to install a license and was able to use the software on January 27th and 28th. Whenever I attempt to run Apprentice now, the Hkey License Admin. is launched.
Mac Pro Processor 3 GHz 8-Core Intel Xeon E5

This page has some licensing FAQs; I've found lots of good help there:

https://www.sidefx.com/index.php?option=com_content&task=view&id=1039&Itemid=273 [sidefx.com]

Having installed this on the mac recently, I can say that the installer asks if you want to install “apprentice non-commercial licensing.” So it is a license, just not a commercial one. Once you do that though, you shouldn't continue to be prompted by the system. I assume your user account is setup as a system admin on your mac? If not, it might be that certain files are not getting placed or their permissions set correctly when you do the install.

As far as I know, there's only one installer for all versions (Apprentice, Indie, FX, etc.) The app packages each up in the Applications directory on the mac in its own little mac app wrapper. I just run the FX app and the apprentice part of the licensing takes care of itself. So as long as your OS version (10.9) matches the download, you've got the correct installer.

If nothing's working, you could always do a fresh install. There's a uninstaller in the app folder, if I remember correctly. Run that, clean everything out. The do a fresh install, making sure to install the non-commercial, apprentice licensing. Once you've done that, you should be good to go.

(gold leaf) I have read and followed the instructions. I may be missing something but it's unknown as yet. I've learned a lot but it is daunting.

Diagnostic Info attached.
Error Messages Screenshot attached.

(nimajneb) I uninstalled, downloaded and installed the Houdini Apprentice once more. Same problem(s) as before…including a License Admin. window =
ERROR: Invalid Machine Name.

Many thanks, as always!

abstractxyz
(gold leaf) I have read and followed the instructions. I may be missing something but it's unknown as yet. I've learned a lot but it is daunting.

Diagnostic Info attached.
Error Messages Screenshot attached.

(nimajneb) I uninstalled, downloaded and installed the Houdini Apprentice once more. Same problem(s) as before…including a License Admin. window =
ERROR: Invalid Machine Name.

Many thanks, as always!

Are you sure that you followed the instructions correctly ? Did you select “apprentice license” after the installer finished the installation ?

jopa79. I watched especially close for the apprentice license the second time I downloaded and installed. There was no such choice-option during the install. The diagnostic info file is attached. Do you see something obvious? There are two (unknown) and there is the ERROR: Invalid Machine Name.

Hello all. Problem solved. I changed the license server name from an ip address to my machine name. I spent hours however and went down many rabbit holes.
Your comments were of great help – so many thanks.

From my experience, even when you are installing apprentice version, make sure you checked the commercial license during the installation. It worked for me.