At the first stage of any release, be it Music, Books, Animations, etcetera, creators can set up exclusive content that can be audio, video or image content that will only be accessible to those who purchase a copy (if necessary, see How to create a Music, Art, Books and more drops in SPOZZ).
This is very useful for those launching a book, for example, so that the content of the book is only accessible to those who buy a copy of it.
Meanwhile, if an artist releases a song, they can also add exclusive content, such as a video for their fans, for example.