Giấy phép
From LimeSurvey Manual
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License Version 2 or later as published by the Free Software Foundation.
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: http://www.gnu.org/licenses/gpl.html