How Do You Track Your Ad Spend?

As c t c, we've traditionally been fairly slow to want to spend money advertising to repeat customers. If it's a c p g brand ith a consumable product, you run a pretty big risk of canbalizing a future order by offering a discount on a present order. And when yhou're past that 60 days, you know, hoave the sense of whether not tat customer came back, you know. So how are you talking to that customer there, versus how were you talking to them before? And if you can start digging into this in certain ways, you can start thinking about which medium is best.