If you provide your API information for one flight, I think Easyjet's system records the info. and applies it to all existing bookings. I had already booked flights for this month when they were originally released, months ago; when I recently booked flights for next April, I was asked for API details which I provided. I then went into this month's flight details to add API and they were already recorded as received. Try checking your details and I think you'll find that Easyjet have done the same for you. Good luck !!
