Why Pay for Free Software
If Open Source products are free, why should you contribute to the author or license the software?
Where else would you expect to get something for nothing? Paying even a small amount to the authors encourages them to continue development and maintenance of the software you are using.
Most GPL product licenses require that you have a visible link to their website. Some products allow you to remove this link if you contribute a specific licensing fee.
Many Open Source advocates disagree with this paid licensing model, but we believe it is very reasonable.