Add a paid plugin/add-on that requires further configuration/setup. Provide support for the added plugin/add-on (configuration/updates), this does not include fixing errors with the plugin (contact the developer). Pending on the plugin/add-on there may be further fees from the plugin/add-on provider or service required by the plugin/add-on. Also, regularly checking your website for out of date plugins, themes, translations, and WordPress itself and updating them.