How to know what coupon was used

I received an order showing a discount but can't find on the order which coupon was used. Is there a way to find out?

Which version you are using, because coupon code should see their on invoice and in order details.

should be a tab toward the top of the order saying promotions

I'm still functioning on 1.3.5 SP2 as I haven't completed my conversion to 2.2.3 yet. So all I see on the order is Act on behalf of.