Saving individual tabs to your library is not supported yet.
Workaround:
The most effective workaround is to save sections of your content and then add those saved sections to your tabs.
Save Sections: You can find instructions on how to save sections in our help article: Reusing Content Across Your Rooms: Saved Sections
While this method requires a few extra steps, it allows you to efficiently reuse and organize your content within your tabs.