Hey there, Phan Quoc Luu
The student subscription lasts for 1 year and will expire one year from when the subscription was first enabled. If the subscription has expired after a year, please can you re-register for the student subscription here: https://azure.microsoft.com/en-us/free/students?msockid=012fee8ffecc600a2c82fb63ff776173
You can find out about eligibility for the student subscription here: https://learn.microsoft.com/en-us/azure/education-hub/azure-dev-tools-teaching/program-faq#azure-for-students
There is an article here on how to reactivate a student subscription through cost management here: https://learn.microsoft.com/en-us/azure/cost-management-billing/manage/azurestudents-subscription-disabled?source=recommendations
It doesn't take long for the subscription to be added to the account. I find the process quick and easy. It took me 5 minutes to complete the form using my university email and sign up. Lastly, please don't share personal identifiable information such as your email or subscription ID. If a support engineer needed this information, they will send you a private message to ask for this information.
Hope this helps,
Nathan