Purina considers 30/20 pro plan an "all life stages" food.  Lots of people start a puppy on 30/20 and keep it on that it's whole life.  The main purpose of a puppy blend is less calories in an attempt to keep people from having overweight puppies.  I personally feed pro plan large breed puppy until they are one year old then switch to 30/20.  However, as I said the main thing is don't let your puppy carry excess weight.  It's the easiest and one of the most important things we need to be doing as owners.