I've tried to throw in bits of extensible knowledge in my con games, to give the players a sense of the arc of discovery that's a huge part of campaign play. And occasionally some player has volunteered a brief in-character reaction of, "Oh, hey, that's cool to know/have." But the players don't have an actual reason to care, and that's a mismatch for one of the strongest dynamics in campaign play.
So maybe I should give them a reason.
My first thought is to label their progress on the character sheet, but tracking non-mechanical assets like "this earl likes me" has never worked as a reward (as opposed to, say, erasing your Sword skill of "4" and writing in "5" -- folks love
My second thought is to pause play for a "what have y'all learned?" chat right before the game's climactic scene, with the understanding that everything you've learned is a potential asset for that scene. But (a) I'm not sure how I'd represent those assets mechanically, so the chat would just be a review and reminder, and (b) historically, some of the most fun moments of creating an asset out of learned stuff have come during climactic scenes.
My third thought is to make up some convention-only abstract mechanic. Maybe at the end of the game, you list all the things you learned, roll that many dice, and then level up or something depending on the result. But dammit, I can't have people leave the table thinking that's how the game actually works...