He hadn't 'bargained on' how his new position in the company would change the way people treated him. [=he was surprised by how his new position changed the way people treated him]
You're allowed to go to the football game tonight, but I expect you to 'keep your side of the bargain' [=do what you agreed to do] and clean your room.
They've agreed to turn the land over to the state, and the state, as its part of the 'bargain', has agreed to keep it undeveloped.
(..) ...but you were never interested in any woman. She isn't just any woman. I see. How do I know you'll keep your bargain? I'll make the arrangements with Laszlo in the visitor's pen. I'm gonna miss you. You're the only one here who has even less scruples than I. Thanks. (..)1942 Casablanca
(..) Berger, Norwegian. At your service. I'll meet you at the bar later. We don't want the ring, but thank you for showing it to us. - Such a bargain. That is your decision? - It is. - Monsieur Laszlo, is it not? - Yes. Captain Renault, prefect of police. What do you want? (..)1942 Casablanca