Hi Bernardo,
Thanks for reaching out and thank you for using Crio Pro WordPress theme!
Your Connect key is used to unlock additional premium features in our plugins and themes, including the removal of the Special Thank attribution link in the footer. You can locate all known Connect keys associated with your account under the Connect Keys section of the BoldGrid Central dashboard. Once you have your key you can connect it to your website by navigating to Settings > BoldGrid Connect and adding it there which should then unlock the ability to hide the attribution.
I hope this helps! Please let us know if there’s anything else that we can answer for you.