@Mohsen Akhavan
Thank you for your post!
When it comes to pricing related issues, you'll have to reach out to our sales team for more accurate details. From your issue details, I'd also recommend leveraging the Pricing Calculator so you can get a more accurate depiction of your expenses after your Azure AD Trial ends.
Additional Links:
Azure Active Directory (Azure AD) pricing
Azure Active Directory plans and pricing
If you have any other questions, please let me know.
Thank you for your time and patience throughout this issue.
----------
Please remember to "Accept Answer" if any answer/reply helped, so that others in the community facing similar issues can easily find the solution.