Please read our Plesk ServerShield guide.
Option A - Installation - Plesk with pre-installed Cloudflare ServerShield Plesk 12 and higher ships with a pre-installed Cloudflare ServerShield SDK Extension. Under the Plesk Control Panel Home page, click “Install”. After successful installation, Cloudflare is added to “Links to Additional Services”. If you don’t see ServerShield on your Plesk 12, skip to Option B.
Option B - Installation from file Under Server Management >> Extensions, click “Add Extension” and upload the extension .zip file, which you can download from www.plesk.com/extensions
Please note, ServerShield supports CNAME integration only.