How do you know if a user has paid at affiliate website?

Question

I have a question about the way of affiliation commission in websites.
I understand that the websites like Skyscanner earn commission when their users have actually bought flight tickets at the flight company through their link.
The question is, how would Skyscanner knows whether the user actually has bought the ticket, or just exits the website in the middle before payment? Is it the information the affiliation website should provide?

Answer 1

So when you click on the link provided in Skyscanner, this link will have an Affiliated ID which is given by the flight company. Using this ID, the flight company will give the commission to Skyscanner if the user has really made the purchase.

So yes it's the flight company that will provide data to Skyscanner if the user has made the purchase or not.