If you are using Phlox free and now you want to immigrate to Phlox Pro you just need to follow below steps:
- After you have purchased Phlox Pro and downloaded the installable zip file from your Envato account.
 - Download and install Phlox Pro
 - Backup your website for extra safety with Duplicator plugin
 - Return to themes page and activate Phlox pro
 - Download and install Essential plugins
 - Check your site and if everything is fine, then you can remove Phlox free theme
 
Note: All you settings and content on Phlox free will be fine on Phlox Pro as well and you will not lose them.