Keep a track of piracy activity? What? Are you serious? What would anyone want to do that? Ideally that’s exactly what you would NOT want to do. But if you aren’t careful about your online pirating activity and are downloading away movies, songs, videos, etc. illegally then there’s a good chance that your IP address can be traced to see what exactly you are downloading.
iknowwhatyoudownload is one such website which takes a dig at tracking the torrents downloaded and distributed by IP addresses. Simply speaking, the website works by parsing torrent websites and monitoring DHT network to collect information about torrent files and thus the result aren’t accurate. However, accuracy of torrents aside, what is important is the fact that you, the user, can be tracked and linked to having downloaded a certain torrent.
This also implies that the enforcing authorities can, in theory, devise mechanism to trace torrent downloads and link them with IP addresses without much difficulty. You can use the website by visiting its english version and see for yourself. Don’t forget to perceive the results with a pinch of salt.