Selling Plugins Themes

There is a thriving premium plugin directory at CodeCanyon.

You can totally sell your themes and plugins, however they must remain licensed under GPL.

In terms of making a living, this may be educational https://faq-tastic.com/faq-tastic/goodbye-faq-tastic-pro/ Not saying don’t give it a try, but have realistic expectations.

i have created a plugin to do this. you can try the free version at https://www.ads-software.com/extend/plugins/sell-my-plugin/ and if you are one of the few lucky people the pro version is being given away at https://www.landry.me/extend/plugins/sell-my-plugin/