If you set your Amazon Prime Rewards Visa Signature as your preferred payment method on Amazon, your Prime membership will automatically be charged to the card upon renewal.
You may choose to cancel your Prime membership at any time and continue using your Prime Rewards Visa card, but if the Amazon account associated with your card no longer has Prime membership, your rewards rate at Amazon and Whole Foods will drop from 5% to 3% cash back — the same rate you would earn with the Amazon Rewards Visa card, which doesn’t require Prime membership.