Hey Jordan,
Thank you for reaching out to us. The conversion option won’t appear in the Appearance > Themes section but it will be available in your Themeco’s dashboard. Simply navigate to the licenses page https://theme.co/apex/licenses and there you’ll see the Go Pro label under X product:
Once your license is converted from X to Pro, the Pro theme will be available in the Themeco’s dashboard to download and then you can install Pro like any normal theme either via FTP or via your WP Admin > Appearance > Themes > Install and activate.
But before doing that, backup your theme settings by downloading the XCS from the the X > Validation > Theme Options Manager. After you install and activate Pro theme, you can go to Pro > Validation > Theme Options Manager and upload the XCS file again to make sure that all X settings are imported to Pro theme.
Hope this helps!