So, I finally got around to going into the AppleCare+ Legal Terms and Conditions.
Who I spoke with yesterday, was incorrect. If you buy AppleCare+ upfront for the 24 months prepaid, the service is for 24 months. The terms I copied below, says the following about renewal of the Single-Pay Plan. It's certainly not clear under what condition Apple might offer a renewal to a Single-Pay Pan or what it could cost.
"(j) Each Monthly Plan will renew automatically, unless cancelled, at its original Plan purchase price. Apple is not obligated to renew any Single-Pay Plan. If Apple does offer renewal, Apple will determine the price and terms."
But it's clear from the Legal Terms the Monthly Pay plan continues until the purchaser cancels or Apple no longer has parts available to fix a device.
"Plan coverage begins when you purchase the Plan and continues, unless cancelled, through the date specified in your Plan Confirmation (the “Plan Term”).
For Monthly Plans, your Plan Term is one (1) month. Your Plan will automatically renew each month unless cancelled as set forth in the “Cancellation” Section 9 below, including in the event that Apple is no longer able to service your Covered Equipment due to the unavailability of service parts, in which case Apple will provide you with thirty (30) days’ prior written notice of cancellation, or as otherwise required by law.
Monthly Plans may not be available for all Covered Devices. For Covered Devices where Monthly Plans are available, you agree to have the credit card, debit card or other authorized payment source i.e. Apple Pay (the “Payment Source”) used for your initial Plan purchase kept on file to automatically charge in advance of the first day of each month following your initial purchase to renew your Plan unless cancelled. If your Payment Source cannot be charged for any reason, and you have not otherwise made the appropriate renewal payment on time, your Plan coverage will cease from the renewal due date. Apple has the right, but not the obligation, to accept any late payment and allow renewal from the date of late payment.
For Single-Pay Plans, your Plan Term is two (2) years (or three (3) years for Apple Watch Edition or Hermès). Apple is not obligated to renew your Single-Pay Plan. If Apple does offer to renew, Apple will determine the price and terms. "