My son is 14 months. Is it okay for him to be eating jarred baby food? If so what age should he stop?

Big boy food! He is probably ready to start transitioning to table foods and soft chunky foods like pieces of bananas, chunks of soft potatoes and veggies, scrambled eggs and small pieces of regular foods. Of course it's ok you are still doing transportable foods, in jars, but he will start noticing other options and is probably ready. Slowly transition and be amazed!
Should be fine. At 14 months, it's fine for a healthy kiddo to be eating baby food. Generally, we suggest that kids begin to transition to "big-people food" when they show an interest and start asking/reaching for it. Remember to take it slow and introduce one new food at a time to get a feel for what they like/don't like and for any sensitivities/allergies.