Kindle Kids' Book Creator

I've got a customer asking if an e-book license is required for publishing a book using Kindle Kids' Book Creator. I was unable to determine from their documentation if the fonts are embedded in e-book formats or if they're rendered images or vectors. I've seen lots of picture books on Kindle where the fonts weren't embedded so I think they're probably not embedded. Does anyone know anything about this system?

Kindle Kids' Book Creator
Kindle Kids' Book Creator PDF manual