Plugins not listed on WordPress.org
Most plugins come from the official WordPress.org directory, but not all. Commercial plugins are often sold on their makers’ own websites, agencies build plugins for a single site, and some plugins are paid versions of free ones. These plugins don’t appear in the directory.
Why it matters
Section titled “Why it matters”There’s nothing wrong with a plugin from outside the directory. Many well-known commercial plugins are distributed this way. What changes is where updates and support come from: WordPress only knows about updates for plugins in the directory. Other plugins need their own way to deliver updates, usually built into the plugin and often tied to a valid license. When the license expires or the maker stops selling the plugin, the updates stop too, without WordPress noticing.
For a custom-built plugin, updates depend on whoever wrote it.
What influences it
Section titled “What influences it”WordPress: Which plugins were installed, and from where. The maker decides how updates
are delivered. A plugin can declare its own update source in its header (Update URI), which also
keeps WordPress from mixing it up with a directory plugin of the same name.
In Permo
Section titled “In Permo”In System info, tab WordPress, the Active plugins list marks these plugins Premium or custom, without a color, and the filter of the same name shows only them. A plugin counts as premium or custom when it has no entry in the directory, names its own update source, or gets its updates from elsewhere. Permo asks WordPress.org only about the other plugins.
For premium and custom plugins, Permo has no data on maintenance or on the WordPress version they were tested with, so they never count on the No longer maintained and Not tested cards. An update they report to WordPress still shows as Update available; see plugin updates.