Once you recommend a user to any product/service (usually subscription program or products which require recurring payment per month), you earn a fixed commission when a registered user pays his next bill. Several of the companies offer recurring commission for fixed time & many companies provide exactly the same for an eternity. All of it depends upon company advertising coverages.
How does affiliate programs work?
Get your personal affiliate link (provided in your personal dash board, when you sign up in any of the affiliate sites) and then place it on your own web site or send it to your own readers. Or, use any of the promotional tools like banners and peel-away ads which will be provided by affiliate. Anytime someone clicks on the link with your affiliate tracking number – they have been enrolled! And as soon as they purchase one of your promoted solutions, you receive a commission!
If you are looking for list with the best affiliate programs with residual income you should definitely check one of these posts: