7-Zip
      ~~~~~
      License for use and distribution
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

      7-Zip Copyright (C) 1999-2005 Igor Pavlov.

      This library is free software; you can redistribute it and/or
      modify it under the terms of the GNU Lesser General Public
      License as published by the Free Software Foundation; either
      version 2.1 of the License, or (at your option) any later version.

      This library is distributed in the hope that it will be useful,
      but WITHOUT ANY WARRANTY; without even the implied warranty of
      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      Lesser General Public License for more details.

      You should have received a copy of the GNU Lesser General Public
      License along with this library; if not, write to the Free Software
      Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

from FAQ:

Can I use 7-Zip in a Commercial Organization?

Yes, 7-Zip is free software. You can use it in any computers. You don't need to register or pay for 7-Zip.