Does each user on my Vestaboard need to purchase Vestaboard+?

No, all users on a Vestaboard will have access to Vestaboard+ content.

Each Vestaboard+ purchase is associated with one Vestaboard display. Any user added to a Vestaboard with Vestaboard+ can take advantage of its growing library of content and tools.
Learn more about the overall benefits of Vestaboard+ at vestaboard.com/plus.