Tip: Microsoft 365 Dev Program

Microsoft has a program that you can get a free Microsoft 365 license for Dev purposes.

Include on this program:

• Includes 25 user licenses for development purposes
• Preconfigured for sideloading Teams apps
• Fully loaded sample data with 16 sample users, user data, and content to help you model your solutions.
• Easy access to pre-provisioned core Microsoft 365 workloads and capabilities (Windows not included), including:
  • All Office 365 apps
  • Everything you need for Power Platform development
  • Office 365 Advanced Threat Protection
  • Advanced analytics with Power BI
  • Enterprise Mobility + Security (EMS) for compliance and information protection
  • Azure Active Directory for building advanced identity and access management solutions

Microsoft Docs:

https://docs.microsoft.com/en-us/office/developer-program/microsoft-365-developer-program

Dev Program:

https://developer.microsoft.com/en-us/microsoft-365/dev-program 

As long as you are using it for development the licenses do not expire.