Hi,
Live events can be scaled up to 10,000 participants and can include all-hands meetings and public webcasts.
To schedule a live event, users must have:
An Exchange Online mailbox.
An Office 365 Enterprise E1, E3, or E5 license or an Office 365 A3 or A5 license.
A Microsoft Teams license.
A Microsoft Stream license.
Here you can find the entire information you need :
https://learn.microsoft.com/en-us/learn/modules/m365-teams-collab-manage-meetings/live-events
GOod luck !