Amazon doesn't inform users when the year is up and your card is being charged again (unless the card has expired or some other issue).
They've become pretty good, however, at tracking/surveilling their users to "improve services" and spam your inbox with product offerings but they can't manage to let you know when charging you for Prime.
In contrast, I use a prepaid cell service that I set up to charge monthly. The day before a CC charge, I get a SMS message informing me that my card will be charged. The next day, I get a confirmation SMS about the results.