For that, Click on the setting, it will redirect to the activation key. Copy the key from the account and paste it there.
When you click on the Save button, there one notification will appear “Your Key Successfully Installed”. If this notification will not appear it mean you did anything wrong, please do it again, still, the issue will not solve, contact to us by mail or fill out a form on the support page.
Once license will have activated, other tabs would enable like integration and Form setting.