NPS Community Edition are distributed under the terms of the Gnu General Public License (GPL) Version 2. Open source licensing provides a unique opportunity for the open source community and for those developing open source software. You should be aware, however, that the GPL is quite restrictive. For example, the GPL license stipulates that any extensions added to the base GPL product also become subject to the terms of the GPL - which include not being able to restrict the use, copying, modification or redistribution of that software

NPS Professional Edition and Enterprise Edition are distributed under a Commercial License for customers who are unable to abide by the terms of the GPL license. A commercial license offers many customers a degree of flexibility not provided by the GPL. Professional Edition can not be reselled,and can not run for enterprise hosting service too.