JpGraph is released under a dual license. For non-commercial usage the library is released under QPL 1.0 (Qt-License) and for professional use it is released under the JpGraph Professional License. See Appendix B. JpGraph Professional License for more details regarding the exact wording of the license. The goal the license have is to be simple, fair and help recover some of the development cost and hosting services that the library development brings with it.
Broadly speaking commercial use is defined as
a) The library is included as an integral part of a product that is sold with a cost that exceeds the cost of the distribution medium.
b) The library is offered as a WEB service for a fee
c) The library is used in an intranet in a company with more than 2 employees
One license entitles the user to install the library on one single physical machine which may run one or several logical servers. In addition it also entitles the license holder to install one version of the library on a separate development server. The professional license is perpetual and is valid for one major version.