Torrenting and illegal downloading files.?

Short answer, an ISP is required by law to keep logs of every I.P. address on a customers activity for a minimum of 3 years. If someone is seriously looking for theft of media or files, all they need do is get a court order for your ISP to see where you have been. That being said, If they haven't come after you yet, they most likely won't. That is unless you were downloading and uploading tons of files.