@BCSecA Thank you for reaching out to us, researched on your queries related to Microsoft Defender EASM.
Query 1: how to spin it down after the 30-day trial if it does not fit our needs.
All resources will receive a 30-day free trial. During this time, you will have access to all functionality, and you will see a message indicating how many days are left in your free trial.
What happens on Day 31 -
Option 1: Delete the resource before the end of the trial and billing will not start.
Option 2: if you want to continue using it, the billing charges will begin.
For more information related to Defender EASM - Refer to this
https://www.youtube.com/watch?v=gwgPdboZPiE which covers Microsoft Defender External Attack Surface Management Architecture, Key features and use cases.
Overview - https://learn.microsoft.com/en-us/azure/external-attack-surface-management/
Let me know if you have any further queries, feel free to post back.
Please remember to "Accept Answer" if answer helped, so that others in the community facing similar issues can easily find the solution.