What is the GPL?
When WordPress plugins and themes are released they’re typically licensed under the GPL (General Public License) – this spells out the rights and limitations to using the software.
Whilst licensing under the GPL isn’t a requirement, it is the preferred license as it used for software in the WordPress plugin and theme directories.
The GPL is all about making sure software is free to run, study, share and modify. This makes the software is free to distribute (and modify) as long as you acknowledge the author.
GPL and premium software
Whilst the GPL is about free access to open source software it doesn’t out rule charging a fee for the distribution (access to and download) of the software (and updates).
When you purchase a “premium” plugin or theme that is licensed under the GPL you’re really paying for distribution and access to support.
Enter the grey market
Nothing in the GPL forbids you from taking someone’s software and redistributing it (as long as you acknowledge the author) – in fact it encourages it because it’s what makes open source software grow so quickly.
Some people take advantage of this by simply taking the software and adding their own price to access it, normally without support or updates.
What I find interesting is there are markets dedicated to this activity – where you pay a few dollars instead of the full price to download the software – most don’t even hide that they’re a third-party.
Whilst this is perfectly legal, it undermines the value of the GPL and the business model that supports the development of the software. Without the income developers will be forced to focus on other activities or release under a more restrictive license.
Ultimately purchasing the software from the developer provides you with updates and support and funds future development that is in everyone’s interest.
For more information on GPL licensing and fees see: