Nope. Anything you purchase from the Marketplace does not count towards your quota. The one caveat is if you download a marketplace package (some art packages have this option) and upload it to your personal library in Roll20 - that will count towards your quota. That being said if you just purchase a set, you'll be able to search for then in the Roll20 Art Search and pull them to the tabletop. You don't need to upload the images to your library.
