Do other IDEs built on top of IntelliJ Platform support paid plugins?
JetBrains plans to scale the Marketplace solution to any non-JetBrains IDEs built on top of the IntelliJ Platform (e.g., Android Studio). We are not limiting the availability of the Marketplace solution to JetBrains tools only, so if the IDE built on top of IntelliJ Platform keeps the plugins repository / marketplace functionality from the platform, it will work the same way as with JetBrains products.
The support for Community Edition (and other free and open-source editions) of IntelliJ IDEA-based IDEs, as well as all IDEs built on top of open-source IntelliJ Platform, has been launched at the beginning of 2020. It might still take some time until the relevant changes arrive to third-party IDEs (depends on their release cycle), e.g., Android Studio will support paid Marketplace plugins after Android Studio 4.0 is released.