Hi @Cédric Taku
If your subscription has not expired, it will automatically renew, as long as you use it (i.e. make at least one Graph API call). As for checking the expiration date, you can do so from the admin portal, under the Billing section.
If your subscription has expired, it cannot be renewed, the subscription and all data will then be deleted within 60 days after expiration. Therefore, you’ll need to set up a new subscription and migrate the data to the new subscription. Refer to this document for creating new subscriptions and migrating data:
Hope this helps.
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