How to install a paid license for ServerShield by CloudFlare extension bought at Plesk online store?
1. Click Retrieve Keys under Tools & Settings > License Management:
This will retrieve the additional paid license from the licensing server and upload it to Plesk
2. Go under ServerShield by CloudFlare extension (at the left menu in Plesk) > Settings tab
3. Fill in the Host E-mail and Host API Key fields if you have already got them.
Note: If you do not have them, click on "Otherwise, create an account and activate this module using <your email>" link and click Submit
4. Go to Server Dashboard tab and click Recheck license link. As a result "Free version" should be updated to "Plus version"