How do I purchase a webinar license? 
To host a webinar, you need to be a licensed user and have a Zoom webinar license. You can purchase these licenses on the Billing page of your Zoom web portal.  

How do I host a webinar?
After purchasing your webinar license, you can schedule your webinar on the Webinars page of the Zoom web portal. When it's time to start your webinar, you can start it from the Webinars page of the Zoom web portal or from the Meetings tab of your Zoom client. Learn more about getting started with Zoom webinars.