7-Zip is open source software. Most of the source code is under the GNU LGPL license. The unRAR code is under a mixed license: GNU LGPL + unRAR restrictions.
You can use 7-Zip on any computer, including a computer in a commercial organization. You don't need to register or pay for 7-Zip.
High compression ratio in 7z format with LZMA and LZMA2 compression
Packing / unpacking: 7z, XZ, BZIP2, GZIP, TAR, ZIP and WIM