Well, the WordPress scene tends to make most of their software open source, including the stuff they charge for. For example, every official WooCommerce plugin

Well, the WordPress scene tends to make most of their software open source, including the stuff they charge for. For example, every official WooCommerce plugin is under the GPL, as is Gravity Forms and Easy Digital Downloads. These are also paid plugins. What this means is that once you download them, you can theoretically use them on as many sites as you like, release edited versions yourself or use them for as long as you need to. What they charge for is basically the following: 1. Updates, since otherwise you have to find and install any updates outside the WordPress dashboard. 2. Support from their support team That's how the WordPress scene in general works for paid products. The products themselves can be used however you like, but a paid license gives you access to support and much improved ease of use as far as updates and things are concerned. So you can make money from open source software, and it would theoretically be possible to have all software as open source.