The license conditions

For the slightly more complicated bit, Neo Technology has chosen very specific licensing terms for Neo4j, which may seem a tad complicated but which actually really support the following goals:

• Promoting open source software
• Promoting community development of Neo4j
• Assuring long-term viability of the Neo4j project by providing for a revenue stream

This is achieved in the following ways:

• The Community Edition uses the GNU Public License Version 3 (GPLv3)
  as its licensing terms. This means that you may copy, distribute, and modify the software as long as you track changes/dates of in-source files and keep modifications under GPL. You can distribute your application using a GPL library commercially, but you must also provide the source code. It is therefore a very viral license and requires you to open source your code--but only if your code directly...