Hello Chris,
Thanks for reaching out to us!
If you are going to use WP multisite we do offer multisite licenses for our products, so in this case that would be the best choice.
If you go without multisite, then probably one business license (3 sites) and one personal (1 site) is the way to go.
I would also like to draw your attention to our nonprofit program for Events Calendar Pro and Event Tickets Plus.
Let me know if this answers your question or if you have more. 🙂
Cheers,
Andras