Before we start:
- Make sure you have a copy of your old theme on your computer in case something goes wrong with the new theme.
- Your setting in the theme customizer will be reset to the initial step.
Update
Go to Appearance > Themes
Activate TwentyFourteen (or another theme)
Delete the old theme (If you are upgrading from the free version this step is not necessary)
Deactivate and cancel fullby-functionality-plugin (If you are upgrading from the free version this step is not necessary)
Upload new version via Appearance > Themes > Install Themes > Upload
Activate the new version and follow the normal installation process