I think you are misunderstanding. In June 2017 they don't offer 2018 passes yet. If you buy 2017 passes, they will set you up on a 12 month payment schedule. All that means is that they let you pay off the 2017 passes over time. If June 2018 hits and it auto renews you are purchasing 2018 passes and need to pay that for the next 12 months....
Similarly, if you pay monthly installments for your phone, you can't just stop the monthly installments and keep the phone...