Gnutella Forums - Getting Caught and downloading rights

How would they catch you
Is it like tracing a phone call or something. Do i need to stay on for a long period of time for them to catch me, or can i just download a song or 2 and get off without any worries.

Here’s another question, what if i bought the origanl cd or cassette (mainly a cassette cause they are harder to put on your pc LOL, i have a lot of money in my cassette collection) at one time, but something happened, like i lost it or broken it. So Since I’ve already paid for it once, i should have rights too download it.