Source : Free On-Line Dictionary of Computing

nagware
     
        /nag'weir/ [{Usenet}] The variety of {shareware} that displays
        a large screen at the beginning or end reminding you to
        register, typically requiring some sort of keystroke to
        continue so that you can't use the software in batch mode.
        Compare {crippleware}.
     
        [{Jargon File}]