The free or educational versions of most apps have build in restrictions, so yes you need commercial license of every app you want to support. Blender is the exception, that's a fully functional free app (no commercial restrictions).
To my knowledge there is no single conversion software out there that can successfully convert complex native 3D scene formats to other native formats (with no error's).
Keep in mind the industry is finally moving forward with universal scene description (USD) (https://graphics.pixar.com/usd/docs/index.html), all major apps are slowly implementing it. Blender already supports USD and as far as I know Maya, Houdini, Unreal Engine4 and Unity also has support for it.
This is good news for 3D stock media developers as it will allow artists to work in a single app and output files compatible with all apps that support USD.
