Sorry if this is an easily answered question, but I haven't seen anything to indicate one way or another, which leads me to believe that it's not possible to filter results based on license.
Hi Hoshua Hamilton, as you said, I notice that MSDN should have a Bing Search Developer Forum (but seems not having currently) and it must be linked from Bing Search API page.
Thanks for your input, we are involving this problem.
Microsoft is conducting an online survey to understand your opinion of the Msdn Web site. If you choose to participate, the online survey will be presented to you when you leave the Msdn Web site.