Hi @Chris_Ridder, welcome to the forum!
If you invite a user to action tasks and view projects in your team and they have an email address associated with your Organization, they will count towards the number of members in your paid plan.
You can certainly invite Guests (users who don’t have an email address linked to your Organization) and they will not count towards the seats in your Organization’s plan.
You can learn more about the different roles in a Organization in this article.
I hope this helps! Let me know if you have any follow-up questions!