In Se7en there was the FBI library register, do/did such things exist IRL?

More like, books like The Anarchist’s Cookbook get stolen so often there’s really no point in buying them. Academic libraries are more likely to collect that kind of material.

ETA - the thing is, patrons hate that we can’t tell them what they checked out a year ago! There have also been incidents like a guy who disappeared hiking near IIRC Clemson and investigators thought maybe they could narrow down a search based on books he had checked out, but there was no record. Hey, tell somebody where you’re going, asshole!

Of course, if you haven’t returned it, the Library Gestapo will find you long before the FBI do, and they won’t read you any rights.

Sorry, I was thinking of my elementary school library and a specialized library at college. Public libraries just had a date stamp.