Macaulay2, its object code, source code, and documentation, are copyright by Daniel R. Grayson and Michael E. Stillman. We permit you to use it either under the terms of the GNU General Public License, version 2, as published by the Free Software Foundation, and as contained in the file COPYING-GPL-2 accompanying the program, or under the terms of the GNU General Public License, version 3, as published by the Free Software Foundation, and as contained in the file COPYING-GPL-3 accompanying the program.
Various packages are included with Macaulay2 and come with their own copyright notices and licenses, see packages provided with Macaulay2.
Some free libraries have been compiled into (or linked with) Macaulay2, and some free programs, or packages of programs, with their libraries, have been compiled and distributed with Macaulay2: