WordPress is distributed as open-source, GPL-licensed code. It's a fascinating license that has empowered a great movement in how software is developed and is certainly worth reading about.
For you, our valued customer, here's what you need to know: Every line of code in every one of our themes and plugins is distributed with the GPL license attached.
What does this mean in practical terms? You can use our themes to do whatever you want. You can use them as much as you want. You can modify them. You can copy pieces from them for your own themes. You can use any line of code for any derivative product. You can even re-distribute them with one catch...any derivative work of our themes, either in part or whole must be distributed as GPL-licensed code. You cannot re-distribute any of our code without granting people the same rights that we are passing on to you. Not just because we say so, but because that is what the license requires.
So there it is! We love WordPress and are grateful for the opportunity that it has provided us because of the GPL license. We feel it is our responsibility and obligation to distribute all of our code with the same license attached. Happy coding!