If you’re interested in the licensing of PowerApps and Power Automate then you may find this page of licensing FAQs useful. It covers a diverse range of topics including trial licences, the Common Data Service, Add-ons, Portals, and AI Builder. Find it here: http://bit.ly/32U9ocP.
There’s an updated (July 2019) PowerApps and Flow Licensing Guide with text added to indicate that the Common Data Service will allow integration with Outlook and SharePoint. Find out more about the facilities enabled for app users here: http://bit.ly/2KIntEm, and find the guide in the brand new PowerApps and Flow section at http://bit.ly/MSLicensingGuides.