The server part of CallMe distributes under BSD license and does not require addition licensing.
Client modules distributes under EULA (End User License Agreement) and require license file.
All required license you can get on this page below.
Commercial licenses are issued for a one year with the need for an extension after the end of the license period.
The trial license is issued for 14 days and after the end of the license period, you need to buy a commercial license or get another trial license.
All kinds of license allow you take a free upgrade of CallMe client during all license period.
All kinds of the license are universal and may use for all types of CallMe client on all of the supported platforms.