Firstly, because they're so new, let's briefly address what these products are and what they do, how to tell if you have them, and what you can do to get them if you don't.
PowerApps is a product that can be obtained as part of Office 365, as part of Dynamics 365, or as a standalone product. It allows users to quickly and easily create business applications that link multiple products together—including Microsoft products and products from outside providers such as Twitter, Facebook, Slack, and so forth—and then publish those apps to the web and to mobile.
The licensing is somewhat arcane, as one might expect, given how many different ways there are to get the product. There's an impact on the capabilities of the users and the administrators that are affected by licensing considerations. Many of the connectors that allow the user to work with outside providers require the more expensive PowerApps Plan 1 or Plan 2. For instance, you can only...