AutomatorWP AffiliateWP Addon GPL Overview:

AffiliateWP is an easy-to-use, reliable WordPress plugin that gives you the affiliate marketing tools you need to grow your business and make more money.

Triggers

FREEUser becomes an affiliate
PROUser earns a referral of a type
PROUser gets a referral of a type paid
PROUser gets a referral of a type rejected

Actions

PROAdd referral to the user
PROAdd referral to user’s affiliate

Tags

PROReferral tags to use the referral information (amount, currency, campaign, etc)