> I agree that only conversions matter, but you should be able to track whether a customer originated from an ad click vs. SEO, whether they clicked one ad and had 4 sessions since, etc.

An ad-click could have been an organic click if the ad wasn't there though, which is where the complexity is.

The ad might have great conversion, but if the customer would have clicked an organic link that navigated to your site anyway then the ad is taking credit for an organic sale.