1. To have a relationship with someone. In this usage, a reflexive pronoun can be used between "associate" and "with." I don't associate with criminals like him. I think he's happy to associate himself with successful people like us.

2. To connect various people or things in one's mind, usually for a specific reason that is unique to that person. In this usage, a noun or pronoun is used between "associate" and "with." I associate the smell of cinnamon with Christmas because of the cookies my mother used to bake every year. He always associates Liz with me because he met us at the same time.