Action Referral Period is another name for cookie period or cookie length.
This refers to the number of days that the advertiser allows users who clicked on one of their tracking links, and came to their website, to complete the transaction or conduct multiple transactions for which the publisher will receive a commission.
For example, a user clicked on a tracking link or an affiliate link from the publisher's site and went to the advertiser's site but did not make a purchase. Later the same customer came directly to the advertiser's site and bought something. As long as the transaction occurs during the cookie period, that publisher will receive a commission for the sale.
Advertisers also have the option to cap the number of transactions that they will pay commission for within the Action Referral Period.
This cap can be 1 to unlimited and is called Action Referral Occurrences. For example, if the number of action referral occurrences is set to 5, then you would be paid commission for a maximum of 5 transactions made during the action referral period, even if you were credited with more than that.