Blurb book's "BookSmart" software is now starting itself up upon boot

Suddenly, starting about a week ago, the Blurb book software, "BookSmart", has begun starting up whenever I start the computer... I don't have any clue why (I haven't recently downloaded any Apple or Blurb updates) and can't seem to figure out how to disable this in either the System Preferences or the BookSmart ones. It's truly annoying, especially for a program I rarely use, and I'd like to figure out how to stop it - ideally without deleting BookSmart, but I'll take what I can get.
Thanks!