Your annual subscription would have been charged and become active at the end of your current monthly subscription. If you changed it from monthly to annual a day after your monthly renewal you wouldn't be charged/notified until 29 days later. In actual terms, if your monthly subscription renewed on the 14th of every month and you had changed it from monthly to annual on the 15th or 16th, a day or 2 after the renewal, the annual subscription would only start on the 14th the following month since your payment is always for the period ahead.
Similarly, if you cancel the yearly subscription tomorrow now that it is active, you still can use Flicktype until October 14 next year since you already paid for the year.