I have a question about internet service providers?

[Southpaw]

It is not months matey, they are now legally required to retain it for 6 years I think and with the storage capacity available these days it might even be forever.
Anyway, here is the UK Governments opinion;
https://www.gov.uk/government/news/commu...-the-facts
It is much the same as itemised billing on the telephone network, the two ends of the communication, the originator and the receiver are logged but the content is not.
Also handy for resolving billing disputes by the way.
So yes they have to, and for a very long time and for a good purpose as we like to feel safe from terrorists and criminals.
Should give you somewhere to start your research on the subject.
Regards, ex BT Bob.