All plugins and themes, both free and premium are released under GPL Version 2 license. GPL2 License file is included with each download. To see the full text of the license you can see at official GNU website:
GNU General Public License, version 2: http://www.gnu.org/licenses/gpl-2.0.html.
Free plugins can be downloaded from WordPress.org website. But, premium plugin (or Pro edition as they are also referred as in many instances) are not free, and before you can download them you need to buy one of the editions available.
The current licensing system is active from December 1, 2013.
To get more information about old licensing system (in use before December 1 2013), you can check out this page: Old Licensing System.
Pro Plugins Licenses
All plugin licenses include access to support forums, knowledge base, downloads, plugin for direct updates (via Dev4Press Updater plugin) for a full year starting with purchase date. Here are the differences between licenses:
- Personal – This license is valid for use on 1 live website. It can’t be used on multisite installations.
- Business – This license is valid for use on 5 live websites. It can’t be used on multisite installations.
- Developer – This license is valid for use on 50 live websites. It can be used on multisite installations. With this license, you get access to Priority Support tickets system.
- Enterprise – This license has same rules as the Developer license, but it is valid for the unlimited number of websites. This license can be purchased on request only. Price for this license is 4 times the price of Developer license.
Dev4Press Plugins Club Membership has all 4 license types also and includes all plugins available. Pack contains access to all the plugins and addons for plugins.
All licenses are valid for one year. That includes download, automatic updates, access to support forums, priority support (for developer licenses) and documentation. After that period expires, you can continue to use the last version you had downloaded, but you can’t get access to download or support and knowledge base access. One month before your license expires (and again 2 weeks and 1 week before expiration) you will receive an email reminding you that license will be expiring. These emails will contain renewal offer that will contain discount for 30%. This renewal offer is valid for a limited time, and you can use it to renew product up to two weeks after it expires.