Why can't I see my licenses after formatting my computer?
Make sure your computer has the same machine name as before.
Houdini licenses are bound to the machine name and hardware.
If you don't know the original machine name, you can log into your account at www.sidefx.com/services. Under License Manager, go to Manage your licenses and look at the SERVER column heading.
Once you rename your computer, reboot and see Lost licenses