So your friend, say his name is Roger, signed up online for a magazine using the name Fred. Yeah, and I'm the queen of England.
This person didn't attempt to use your friend's credit card or anything to pay for it, right? Just used his name? People use false names all the time online. As long as there was no attempt to defame or cause any sort of loss, then simply signing up for a magazine using a false name is nothing.
Signed,
HRH the Queen of England