For now, opening the Hulu Live TV app will redirect you to the main Hulu app, which will service both the $40-per-month livestreaming service and the standard $8-per-month Hulu content library. It's unclear when the former will be taken off the App Store for good, but the main app's update log confirmed it will happen:
"Heads up! We are saying goodbye to our Hulu with Live TV app so you can have all your TV in one place. We will soon unify the two Hulu apps currently available in the Apple App Store, Hulu with Live TV and Hulu, into one great on-demand and live TV viewing experience. We will let you know when this happens for good."