I've had an active subscription for years and I am trying to enroll my iPhone 12 Pro Max for screen care but when I try to add it in the Device Care app, the only options is to pay $3.99 and I thought the first device is supposed to be free.
Have you been renewing your subscription using the Norton Automatic Renewal process? That is a requirement for the 'free' Device Care service. If you have been purchasing new subscriptions each year you do not qualify and have to pay the current price.