Fanpage Persistent Menu – Plugin WordPress
The persistent menu can be set for your bot to help people discover and more easily access your functionality throughout the conversation.
The Persistent Menu is always available to the user. This menu should contain top-level actions that users can enact at any point. Having a persistent menu easily communicates the basic capabilities of your bot for first-time and returning users. The menu will automatically appear in a thread if the person has been away for a certain period of time and returns.