Hey @muchcharles!
You should probably check out the FAQ on the marketplace for more information on what you can and cannot do with purchased content. It’s quite informative. To further expand on what Chance said, you can use Marketplace content in your work so long as it doesn’t get redistributed. As he mentioned it will need to be in a cooked format, so that the people who download your mod wouldn’t have access to the assets from the marketplace you used in your mod as that would be against the terms.