Quit watching your favorite show for three months? I doubt many people are willing to do this.

The Witcher had a complete series drop recently: sign up for a month to watch it, then cancel. The Expanse is going for a weekly recently schedule: once it's done in January, cancel the service.

Unless there's a continuous series of releases that people will want to watch, I'm not sure they'll want to subscribe for an entire year: it surely adds up.