I renewed my AP's online a couple weeks ago, elected to have the voucher paperwork mailed to me, and it specifically states they will be good for 15 months from my anniversary date of the AP's, which is October 2.
Also, we have had AP's for about 7 years now and if we don't have our actual AP's in hand for check-in, then we're just sure to have our vouchers or some sort of printed receipt showing we bought them. We've never been asked for anything other than what we provided. Worst case scenerio, they could ask you to bring your AP's back to them once they are activated.