2.8. GPL and LGPL licenses The syslog-ng Premium Edition 7 Administrator Guide
Starting with version 4 F1, the syslog-ng Premium Edition application is based on the syslog-ng Open Source Edition application, and includes elements that are licensed under the LGPL or GPL licenses. You can download the core of syslog-ng PE here. The components located under the
/lib directory are licensed under the GNU Lesser General Public License Version 2.1 license, while the rest of the codebase is licensed under the GNU General Public License Version 2 license. External libraries and other dependencies used by syslog-ng PE have their own licenses, typically GPL, LGPL, MIT, or BSD.
Appendix C, Open source licenses includes the text of the licenses applicable to syslog-ng Premium Edition.