Update: 13 August 2023 - Power Apps Licencing has change considerably since this post, for example here is updated information on Power Automate licencing.
My Technical Working Notes for Microsoft Technology: App Insights for Power Platform - Part 9 - Power Automate Licencing (pbeck.co.uk) A major change in naming and cost has been release August 2023.
Overview: The Total Cost of Ownership (TCO) is key to any project. I recently was asked about a project that wanted to use Power Apps for external user access, the data is in the dataverse/CDS) and their are tons of workflows. The cost of buying a per app licence for external users is a non-started (without volume discount $5 or £3.80 per user per month and the only viable options left are:
Design by Cost:
Write the front end using free to distribute front end application (i.e. ReactJs, Angular, C#, Flutter, Blazor,...) and all the flows using the per-flow licencing model. Per-flow licencing is crazy expensive as it is per flow and my users have lots of flows when the login once a year. So per flow is also not an option with a custom front-end. At Ignite 2022, Microsft announce a new Power Automate Embedded SDK with pay as you go pricing, this may be a good option, but's its untested.
The $5/month/app plan doesn't really work as users login over the last few months of the year and all users would need to be licenced all year around so $60 is way too high. The Power Apps Pay-as-you-go Plan allows costs $10/£7.45 per user that logs in during a month. So in my case an average user logs in 2 times in a year with the monthly consideration, so i'm still looking at $20 per year.
User/Per App/month: £3.80
User/Month (multiple apps): £15.10
Active User/app/month Pas-as-you-go £7.45
Power Apps Portals/Power Pages/Dynamics Portals is my last hope. The licencing is based on per login per 24 hrs. So a user that logs in three times in a 24 hr period is considered 1 licence. If the user logs in on 4 different dates at any point in the year, the client is changed for 4 logins. Need to buy the licences in advance each month. Sold in blocks, the smallest being 100 logins in a month. At the lowest levels, cost is $2 per 24 hour login, but this reduces to a much lower cost relatively quickly. With our expected numbers, we'd get onto Tier 3, and the cost per login is $0.70 per login. If an average user logs in 4 times a year on separate dates, our cost is basically $2.80 per user per year.
Note there is also a Page Portals Capacity licence required. We are expecting an average of 175k page views, which cost a further $200.
13 Oct 2022: Licencing for Power Pages change yesterday, 1) monthly anonymous active users 2) monthly authenticate active users. Prepaid is cheaper than pay as you go, assuming you get you numbers right. https://www.microsoft.com/en-us/licensing/news/power_pages_general_availability#:~:text=Today we are announcing licensing and pricing details,to purchase through prepaid subscription and pay-as-you-go plans.
Summary: In this case, Power Pages is the best option.
