vim-markdown-preview is released under the GPL v3.
The terms and conditions of this license are described below:
Copyright (C) 2009 Robert Gleeson <email@example.com> vim-markdown-preview is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program 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 General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>.
This file(LEGAL.mkd) must be apart of any redistributable packages made from this software. No licenses(including the one pertaining to kramdown) should be removed from this software if you are making redistributable copies.
The kramdown library is used for converting a markdown document into a HTML document, and it is bundled with this software.
Thomas Leitner, the author of the kramdown library.
(The GPLv3 license for kramdown can be found at "./plugin/vim-markdown-preview/kramdown/COPYING" from the root of this project)