When Trellis is the active theme, you can find these settings by logging into your WordPress site and navigating to Appearance → Mediavine Trellis → License
Enter a valid Trellis license here to unlock all the theme settings and features. You can also verify that the license is valid, and for how long.
If you haven't already added your license, you can find it in your Mediavine Marketplace account details.
Don't have a valid Trellis License? Check out the Mediavine Marketplace to get one.