If a customer makes a purchase and then returns it you might
lose your commission. There are some merchants who do not chargeback for returns. These merchants are the exception, rather
than the rule.
With returns the affiliate has not done anything wrong. The
customer has simply changed their mind. Some merchants specify a time period in which chargebacks can occur.
For example, the merchant may specify a 30 day return
period whereby if the customer returns the merchandise within 30 days your commission is reversed for that sale.
After the 30 days you are home free.
If the merchant does not specify these terms in their program
description and you are providing a lot of traffic to that merchant, it would be a good idea to call the affiliate manager
and ask for clarification.