Plugin License for WordPress Plugin by Website Design London

After developed a plugin you plan on releasing to the public your plugin, the software license also include that the plugin is released under just below your plugin header. Remember that this is not a requirement for the plugin to function that it use for perform any functionality, This is to clearly state what software license your plugin uses. The licence statement written in the comment block it also state that there is no warranty of this plugin, If someone decide your plugin destroyed his or her site then it protects you from liability.
Below is a standard of GPL license, Most of the WordPress plugins are released under this:

<?php
/* Copyright YEAR PLUGIN_AUTHOR_NAME (email : PLUGIN AUTHOR EMAIL)

Every user can use this software in free; If you want to modify and make the change in it than you can do and it is under the terms of the GNU General Public License this is published by the Free Software Foundation. We hope that this program is very useful for you, remember that it is WITHOUT ANY WARRANTY; even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. If you want to know more than more details see the GNU General Public License in the web.

With this program a copy of the GNU General Public License along with this program you should have received; if not then write to the Free Software Foundation.
*/
?>
The license start with the year of it, then plugin auther name, and plugin author e-mail in the above comments. Your plugin will be licensed under the GPL by doing this. Under the GPLv2 software license WordPress is licensed. For open source projects this is very common license. Mostly plugins realised under the GPL since plugins are dependent on WordPress to function, or compatible, software license. If you want to know more information about GPL Licensing then visit http://www.gnu.org/licenses/licenses.html/ this site.