Extension developers can use the same mechanism that is used to manage Plesk product licenses to issue and manage license keys for their extensions.
Extension licenses are implemented by means of Plesk additional license keys. In other words, a license for an extension that is installed on a specific Plesk server, is actually a Plesk additional license key issued by Plesk Key Administrator for this server’s Plesk product license key.
The availability of the extension’s functions, determined by a license key, is defined by the contents of the license key body. With it, Plesk additional license keys can facilitate all of the listed licensing models, which covers most developers’ needs.
Additionally, for the rare complex cases, Key Administrator provides the ability to combine custom license keys with Plesk license keys. For more information, see the section Issuing Custom Licenses for Extensions.