Visual Studio subscriptions grant Azure credits as a benefit, but these credits can only be activated once per subscription. If you cancel the Azure subscription linked to this benefit, reactivation is not allowed. This is why you are seeing the "cannot activate the Azure subscription more than once" message.
Since the tenant associated with the Azure subscription no longer exists, this further complicates reactivation. Azure subscriptions are tied to specific tenants, and deleting the tenant removes access to the associated resources.
Log in to my.visualstudio.com using the account associated with your Visual Studio Professional subscription. Verify if your Visual Studio subscription is still active and eligible for benefits, If you have another tenant or Azure account where you can activate the Azure credits, try reactivating the benefit there. However, this is contingent on Visual Studio’s policy of allowing a one-time activation. Since the original tenant linked to the canceled subscription no longer exists, you can create a new Azure AD tenant, for this navigate to Azure Active Directory, click "Create a tenant" and follow the steps to set up a new directory. Sign in to the new tenant and attempt to claim your Azure benefits. Navigate to the Visual Studio Subscription Benefits page and check if the Azure credit benefit is available for allocation to the new tenant. If the benefit displays as "already activated," you can proceed to the next step to utilize your Visual Studio subscription for discounted pricing on a new Azure subscription, you can create a Pay-As-You-Go subscription.When reactivating the Visual Studio $50/month credit benefit is restricted, this approach allows you to benefit from your Visual Studio account. Start by visiting the Azure Portal and navigating to the Subscriptions section. From there, create a new Pay-As-You-Go subscription and link it to your Visual Studio account to access potential discounts. You can then use this newly created subscription for your projects.
Reference:
https://learn.microsoft.com/en-us/azure/cost-management-billing/manage/cancel-azure-subscription#reactivate-a-subscription
https://learn.microsoft.com/en-us/azure/devtest/offer/quickstart-individual-credit#activate-your-azure-credit-subscription
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