@衣里子 紺谷 Thank you for reaching out to us, As I understand you are looking to know how to check whether the license is a trial version or a full purchase. trial license is always valid for 30 days. however you can check the details related to license from the below screenshot within the O365 portal.
Let me know if you have any further questions, 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.