"Help | Register Plugins..." disappears in IntelliJ IDEA Community Edition

Problem

In IntelliJ IDEA Community, Help | Register Plugins... is absent in the menu:

Cause

The bundled Plugin "JetBrains Marketplace Licensing" is somehow disabled.

Solution

Go to Settings | Plugins, enable "JetBrains Marketplace Licensing", click Apply, and restart the IDE

Then the option "Register Plugins" appears: