Amazon has done what many others dream of: I basically forget that I'm paying for Prime every year. And I perceive that it gives me enough value that I don't mind, but I've never actually checked how many orders I place each year vs. the delivery cost for them if I didn't have Prime. By comparison, Google sends me an e-mail every month reminding me how much I'm paying for Google Play Music. I don't mind it, but I won…
The Google method of sending a yearly notification is the idiomatic and proper way of selling a service. The Amazon way is the scumbag way because that's how they charge you without you knowing.