Just started Tresiba, Coupon?

Filled my first prescription. Copay was around $450 but when I went to pick it up, the pharmacist told me they applied a coupon that is good for my first 12 fills that brought it down to $30.

That's clearly awesome, but they didn't give me a coupon or anything, so now I'm wondering if the coupon is on my account for the next 11 fills or if they are going to charge me the full amount.

Anyone know how that will likely work?