This usually depends on what programs you used to pirate it in the first place. Some Torrent clients such as Deluge and Halite will never allow their packet data to be intercepted and decoded / etc. They also don't keep records of torrents and magnet link usages. So either you didn't cover up your tracks, or the ISP is just being stingy. (Time Warner Cable and Comcast for instance, which we don't even have here in Madison, WI are pretty stingy.)
I've only pirated software once, and I didn't even pirate it myself, my mother did, using dial-up with her University Internet connection. The only things I've pirated otherwise are Anime episodes (Sword Art Online and Mushishi and the first six seasons of Pokemon, which, I only got to see up to the half point of Season 3), a single movie, and using a youtube downloader on music I liked. Though that last item, isn't really pirating on me, it's actually the fault of the person posting the music in the first place.





