Usually no. If you already have Microsoft 365 (whether Business Basic, Business Standard, Business Premium, E3 or E5), the licence includes a Power Apps use right for standard connectors — that is, apps whose data lives in SharePoint, Excel-in-OneDrive, Outlook, Teams or one of the other standard connectors. Such apps run at no extra licence cost. Power Apps licences only come into play once you need premium connectors (Dataverse, SQL Server, custom connectors to third-party systems) or Power Automate premium flows (HTTP, custom connectors): per-app from roughly CHF 5/user/active app/month, or Premium (CHF 16.20/user/month) for unlimited apps. We review your licence estate and the planned data backend first — often the existing M365 stack is enough.