AP vouchers (actually, they are called "AP certificates" by Disney) do not "activate" until after a guest physically goes to a ticket booth or Guest Relations and (guests over 18 years old) shows a legal photo ID, and THEN actually goes through the park gate (which can be on a later date than when the guest visited the booth to show ID.)
It is now part of the activation process that the AP does not start "counting down" until the guest first uses the AP at a park gate.
AP certificates have an expiration date (I prefer "use first by date") of Dec. 31, 2030.