Your Indie or full Commercial Houdini file is saved as Apprentice Non-Commercial (.hipnc):

• Ensure that you don't have any Houdini Digital Assets (hda) saved in non-commercial format (.hdanc).
• The asset could also be saved with the .hda extension but still in non-commercial format.
• An asset in non-commercial format will downgrade your Indie or Commercial Houdini session.
• Any assets in the otls folder will be automatically loaded. It will be a good idea to check in this folder first for any non-commercial assets accidentally saved.

Location of the otls folder

Windows: C:\Users\your-username\Documents\houdini18.0\otls

OSX: /Users/your-username/Library/Preferences/houdini/18.0/otls

Linux: /home/your-username/houdini18.0/otls