Yes! If you select the "Bring Your Own Book" mode when you start a new book on Leanpub, you can upload PDF, EPUB and/or MOBI files and sell them directly on Leanpub. This way, if you already have a completed PDF, you don't need to reformat your book into Markdown and use the Leanpub workflow - you can just upload it. On the book's web page, we clearly indicate to customers which formats are available. Of course, if you are starting a new book, we recommend that you use the Leanpub workflow to generate PDF, EPUB and MOBI ebook files directly from your manuscript with one click.