there is nothing complicated. Usually this is indicated in accordance with the conditions: by submitting content (for example, texts, images, video), withdrawal or recall of comments, sending comments, etc.
as far as I remember, it is still possible to choose the type of licensing, as when installing programs: free version, paid, premium, etc ... does this concern this topic?
of course, concerns. The user provides the platform with an irrevocable, non-exclusive, perpetual, worldwide, royalty - free license to use the content.