Run the program for any purpose.
Study how the program works and to change it, so it performs computing as you wish.
Redistribute copies, so you can help your neighbor
Distribute copies of your modified vers, giving community chance from your changes
Free software can come with a price tag. In other words, you can create a GPL theme and sell it for $50, and it would still be free software. Why? Because the user is free to run, modify, and distribute the software or any modifications of that software.
The freedoms of the GPL don’t only apply to the original piece of software; works derived from GPL-licensed software must also adopt the same license, without restrictions or additional terms.
Do I need to license my themes under the GPL?
If you have no plans to distribute your theme then you do not need to adopt the GPL license for your work. The GPL only applies to distributed software. If you are not distributing your software – for example, a theme used only by yourself or on your local machine – you do not need to adopt the GPL.
If you wish to submit your creation to the free theme repository on WordPress.org, it must be 100% GPL compliant, including CSS and image files. Because the freedoms spelled out in the GPL are at the heart of WordPress, we encourage developers to distribute their themes with a 100% GPL-compatible license.