From the license server machine (or from a client that has write-access to the license server):

1. Open the License Administrator (hkey)
2. Select File -> Manually Enter Keys...
3. Copy and Paste each keystring into a text box using Ctrl+V and press OK

Make sure you copy the entire keystring. Failing to do so will cause Houdini not to function.

Each keystring needs to be entered on a separate line in the License Administrator GUI.

A new keystring begins at the keyword: SERVER, LICENSE, INCREMENT, UPGRADE or EXTEND.