Knowledge Base

Available Licensing Models

Depending on the extensions’ functionality and your business model,
Plesk extensions can be distributed under various types of licenses.

Licence type	Details
Free	The users are not charged for using the extension. After it has been installed, all of its functionality is immediately available.
Single Offer	The users paying for such a license gain access to full functionality of the extension. Such a license is usually issued on a per-server basis. An example of an extension with a “single offer” license could be an application that scans the server for vulnerabilities and reports them to the administrator.
Multiple Offers	This licensing model facilitates scalable (multi-tier) offers. It should be implemented when a Plesk administrator has the option of choosing one of the predefined sets of functions or available resources that this extension provides, which best suit their needs. A good example is the Plesk Premium Email extension by Kolab. There, the administrator can choose which license to buy based on the desired number of user accounts.
Freemium	Users are free to download and install the extension, and use a certain part of its functions. Additionally, they are offered to pay for access to its premium features. “Freemium” can be viewed as a combination of two types of licensing described above: “free”, and “single offer” or “multiple offers”.

Note: All extension licenses are in fact lease licenses, which means, they
can only be purchased for a specific period of time (1 month). They
are not perpetual licenses.

Note: An extension that requires a license to work can be installed on a
Plesk server even without a license. This means, such an extension
must be able to interact correctly with and without a license.