If you're experiencing significant blocker given that you can't imagine why the GMS licenses might be restricted, you might not be in the target audience for this game.
Part of the joy of roleplaying games with rich settings is exploring the gaps, implications, and assumptions of the text. If my group earnestly asked a question like, "Why doesn't everyone have a GMS license?", we'd probably have a real good time working together to find out!
All that to say: the most economical and enjoyable solution to this problem is very likely to be your group or GM figuring out something cool together.