OptimizePress – amazingly diverse solution that creates awesome membership areas
ClickFunnels – easily create sales funnels and membership sites that convert
Value Addon – quickly build membership areas with a lot of advanced functionality
Teachable – create your own online courses that you control the prices for
Udemy – a free platform for hosting and your free or paid membership areas
Zenler – make money teaching online courses for free
WP Profit Builder – affordable and badass alternative to ClickFunnels and OptimizePress
Patience – sell online courses from your own website
ProductPress – sell your WordPress content on Gumroad
Member Mouse – feature-rich advanced membership solution for WordPress