I don't have any budget to buy commercial licenses but the libraries I use offer non-commercial free licenses.
How far can I go in regard to monetizing my game without it being considered commercial ? Donations? Do ads count? Optional items purchase?
For example, fmod states in their free license:
This license cannot be used for commercial services, where the executable containing fmod is not sold, but the data is.
What if only some data (optional) is sold?