Hello Mohammad,
Welcome to the Microsoft Community.
Thank you very much for sharing your concern in detail. Generally, you can no longer use your student account after 30-day grace period upon graduating as IT admin of your school organization will disable or reassign your account license to incoming students.
Manage graduating student licenses and content in Microsoft 365 Education - Microsoft Support
As you mentioned, your college account is still active and has not been locked. So logically, as long as you can still log into your account successfully, you can use this account normally (but there may be no data anymore...)
If you have such concern, you can contact the IT Admin of your school organization. They might help you reassign a student license in Office 365 and provide you the steps to move the data that you have.
If there's anything else that we can help you with, please do not hesitate to reply here and we will further assist you.
Best regards,
Serena - MSFT | Microsoft Community Support Specialist