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So there's no legality problem when I share this with my teacher?
If you are giving him the rendered images from the scene, there is no problem.
If you have to submit the whole scene with the models, you better ask your teacher beforehand and tell him that the models are with Royalty Free License and you can't share them, so there are 2 options - he can delete the licensed models after inspecting the scene or if he has to store them, he has to buy a license for them as you did.
Only the .png (or .jpeg) files - no .blend or .obj files.
Like this one: https://imgur.com/a/6oUYK9h
No problems then.