I'm not sure if this is late, but I was just a little bit surprised after playing the game a couple of times.
People were debating on the "right" choices so we can get Kenny to join Lee in searching for Clementine during the final chapter of Episode 4. I've some threads where they posted a list of conversations and choices involving Kenny that affects his friendship with Lee (i.e. "Kenny will remember that" will pop up on-screen).
Of all the choices, there was this mention of the "big 3" situations - saving Duck instead of Shawn, siding with Kenny at the drugstore and helping Kenny in killing Larry/preventing Larry from turning in the meat locker. Most people would say that failing just one of these won't get Kenny to come with Lee.
However, my latest play-through showed otherwise. I helped save Duck, defended Kenny in the drugstore BUT sided with Lilly in the meat locker situation and Kenny STILL went with me voluntarily, even saying that Lee's got his back the whole time.
After that incident, Kenny is a bit hostile and unwelcoming when talking to Lee. I was ok with this at first because I wanted Lee to go alone in searching for Clementine. If you hide the bite, Christa & Omid won't come with you. I was hoping for Kenny not to join, stating that he's been keeping count of the number of times when they're suppose to help each other.
So there, I hope this'll help, especially for those who wanted to side with Lilly in the meat locker and not wanting to carry the burden of crushing Larry's head, and still got Kenny's loyalty in the end.