For the people struggling with the coupon code, here's what I did.
Sign up for the monthly version of the mini plan. You will be charged $5. Then enter the coupon code in the coupons tab from the left pane. You can then immediately upgrade to the annual version of the plan. You will be charged $19 brining the total to $24 for one year (the half off price). It should save the trouble of paying full price for a year and sending an email for the manual refund.
Sign up for the monthly version of the mini plan. You will be charged $5. Then enter the coupon code in the coupons tab from the left pane. You can then immediately upgrade to the annual version of the plan. You will be charged $19 brining the total to $24 for one year (the half off price). It should save the trouble of paying full price for a year and sending an email for the manual refund.