I’ve been working on a game recently that in the future I would like to publish but I was just wanting to make sure that using free downloaded assets of unity asset store and places like SketchUp if I wish to publish the game and sell it on steam for example.
In my experience, you should read the license agreement of the asset you use, or the site you got it from:
You can read more about the different licenses here: https://creativecommons.org/faq/
Some creators require you to give them credit in your “Credits” section.
And some “Free” assets are for personal use only.
If you are uncertain about the license, contact the creator and ask them if you are allowed to use it.