Can I use Arial (font) in my puzzle books?
Puzzle Maker Pro selects Arial as the default font to use for puzzles and puzzle books. A very relevant question is: Can you sell puzzle books where you use Arial to print all the letters and numbers?
Microsoft has a F.A.Q. section about this: https://docs.microsoft.com/en-us/typography/fonts/font-faq.
Long story short: You can use Arial in your puzzle books "Unless you are using an application that is specifically licensed for home, student, or non-commercial use, we do not restrict you from selling the things you print and make using the Windows-supplied fonts"