Libdnf is covered under two separate licenses: GPLv2+ and LGPLv2.1+.
The entire code base may be distributed under the terms of the GNU General Public License version 2 and any later version (GPLv2+). The complete text of the license is available in the gpl-2.0.txt file.
Alternatively, all of the source code in 'libdnf5', 'libdnf5-cli', 'include' and 'bindings' subdirectories of the libdnf source code distribution as well as any code derived from that code may instead be distributed under the GNU Lesser General Public License version 2.1 and any later version (LGPLv2.1+), at the choice of the distributor. The complete text of the license is available in the lgpl-2.1.txt file.
This alternative is provided to enable applications to be linked against the libdnf and libdnf-cli libraries and their bindings to other programming languages without forcing such applications to be distributed under the GPL.