Your company plans to migrate all its network resources to Azure.

The first thing you create in Azure is a subscription. You can think of an Azure subscription as an ‘Azure account’. You get billed per subscription.

A subscription is an agreement with Microsoft to use one or more Microsoft cloud platforms or services, for which charges accrue based on either a per-user license fee or on cloud-based resource consumption.

Microsoft's Software as a Service (SaaS)-based cloud offerings (Office 365, Intune/EMS, and Dynamics 365) charge per-user license fees.

Microsoft's Platform as a Service (PaaS) and Infrastructure as a Service (IaaS) cloud offerings (Azure) charge based on cloud resource consumption.

You can also use a trial subscription, but the subscription expires after a specific amount of time or consumption charges. You can convert a trial subscription to a paid subscription.

Organizations can have multiple subscriptions for Microsoft's cloud offerings.

References:

https://docs.microsoft.com/en-us/office365/enterprise/subscriptions-licenses-accounts-and-t enants-for-microsoft-cloud-offerings