A Microsoft offering that enables tracking of cloud usage and expenditures for Azure and other cloud providers.
In your tenant you can add as many subscriptions as you want, go to subscriptions and click on Add and choose an offer for your subscription, in your case Pay-As-You-Go. https://portal.azure.com/#view/Microsoft_Azure_Billing/SubscriptionsBladeV2
Note: A user with Owner or Contributor role can create an Azure subscription
Reference: https://learn.microsoft.com/en-us/azure/cost-management-billing/manage/create-subscription
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