Reza Rad busts out the calculator:
Licensing in Power BI comes with many options. Understanding which features are included in which licensing plan is always a question for users. In this article and video, you will learn about all the different licensing plans in Power BI, the scenarios for which to use the licensing, and scenarios for which you may need to change your licensing. This article and video are intended to help you to decide the most cost-effective licensing plan for your requirement.
Reza goes into great detail in the post and then answers a lot of questions in the comments as well.