When you add a library item to a page, the actual content is inserted in the document along with a reference to the library item.
.Drag a library item from the Assets panel to the Document window.
To insert the contents
of a library item without including a reference to the item in the
document, press Control (Windows) or Option (Macintosh) while dragging
an item out of the Assets panel. If you insert an item this way,
you can edit the item in the document, but the document won’t be
updated when you update pages that use that library item.Select a library item, and click Insert.