I'm using the web library (and windows program) to read epubs. It works very well. Zotero doesn't remember where I left the book. Only the last heading I passed (?) This works well in books with many subheadings, but in longer chapters it is not as great. I have already moved all my kindle books into Zotero, including novels but I'm not sure I can read novels in Zotero if it only sends me back to the last chapter I started on. (highlighting text and finding the last highlight works, but is not as logical reading fiction).