When you recommend a user to any product (usually membership program or products which require recurring monthly payment), you earn a fixed commission when a referred user pays his next bill. Some of the companies offer a recurring commission for a fixed time (Let’s say one year) & many companies offer the same for a lifetime. It all depends upon company marketing policies.
Affiliate marketing overlaps with other Internet marketing methods to some degree, because affiliates often use regular advertising methods. Those methods include organic search engine optimization (SEO), paid search engine marketing (PPC – Pay Per Click), e-mail marketing, content marketing, and (in some sense) display advertising. On the other hand, affiliates sometimes use less orthodox techniques, such as publishing reviews of products or services offered by a partner.