If he paid just for your stuff and not your friends', he's definitely trying to show that he is interested in you. His interest could be romantic and/or sexual. Have fun, but don't do anything you might regret if it's only the latter.

Paying for a date and a few books is pretty harmless, if somewhat old-fashioned in a lot of cultures. But maybe he just thinks that's what he's supposed to do. However, if he also starts buying you expensive gifts early on in the relationship, be very careful, especially if he's a bit older than you! That's the MO of so-called "lover boys" that like to lure girls into prostitution. Eventually he'll demand something in return and it's only downhill from there.