For some reason it says that the coupon is permanent, what does that mean for an annual subscription? Do I just pay the same every time?
Most of the coupons just stay on your account forever.
I double checked your account, and indeed, your next payment (and every monthly/yearly payment after) will be at the discounted price.
Only way to change this is if you put a different coupon code in, or if an admin removed your coupon for some reason. Anyways, don’t touch coupon things and you should be good.