In addition to its BSD license, it is easily adapted for use by businesses. A total of 18 million downloads are estimated to be made. Government agencies, universities, and companies all use it in some fashion. C++ is the language of choice for this program. Having a very modern templated interface, which works just as well for STL containers is really impressive.
In closing, I think it is one of the best libraries I have come across that is well written. I wouldn't hesitate to recommend it to anyone that knows how to play around with it. There have been continuous improvements to this brilliant product.