Before Oct 15th, PDF Page Merger Pro is in the Giveaway Promo. All users can use the giveaway serial key to upgrade to the Pro version for free.
PDF Page Merger is not the regular PDF combining software. Different from other PDF merging tools combining multiple PDF files to a single PDF file, it was specifically designed for merging multiple pages into one page in a single PDF file. Besides combining all pages into a one-page PDF file, this handy tool can also merge every 2, 4 or more PDF pages to one page and save to a new PDF file. That would be very useful for people who need to create double-sided PDF magazines, collage page PDF eBooks, or save ink for mass printing documents economically.
Source: PDF Page Merger