amxmodx/public/licenses/LICENSE.txt

AMX MOD X LICENSE INFORMATION
VERSION: AUGUST-04-2014

AMX Mod X is licensed under the GNU General Public License, version 3, or (at
your option) any later version.

As a special exception, the AMX Mod X Development Team gives permission to link
the code of this program with the Half-Life Game Engine ("HL Engine") and
Modified Game Libraries ("MODs") developed via the Half-Life 1 SDK as full
replacements for Valve games. You must obey the GNU General Public License in
all respects for all other code used other than the HL Engine and MODs. This
extension, at your option, may also be granted to works based on AMX Mod X.

As an additional special exception to the GNU General Public License 3.0,
AlliedModders LLC permits dual-licensing of DERIVATIVE WORKS ONLY (that is,
Pawn/AMX Mod X Plugins and AMX Mod X Modules, or any software built from the AMX
Mod X header files) under the GNU General Public License version 2 "or any
higher version." As such, you may choose for your derivative work(s) to be
compatible with the GNU General Public License version 2 as long as it is also
compatible with the GNU General Public License version 3, via the "or any higher
version" clause. This is intended for compatibility with other software.

As a final exception to the above, any derivative works created prior to this
date (August 4, 2014) may be exclusively licensed under the GNU General Public
License version 2 (without an "or any higher version" clause) if and only if the
work was already GNU General Public License 2.0 exclusive. This clause is
provided for backwards compatibility only.

A copy of the GNU General Public License 2.0 is available in GPLv2.txt.
A copy of the GNU General Public License 3.0 is available in GPLv3.txt.

Some components of AMX Mod X use a license other than the GNU General Public
License. You must also adhere to these additional licenses in all respects. See
ACKNOWLEDGEMENTS.txt for further details.