Plesk

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.