In order to add new users to your account, you need to follow the next steps.
Step 1
Login to your account in the web app. Upgrade/change your plan with the number of licenses if needed from the Billing page.
Step 2
Click on the Licenses link in the top bar.
Step 4
Add the email addresses of your users in the users field. This acts as a user seat/license.
Users can be removed from the same panel and you can assign the seat/license to another email address at any time.