If you are on partial-domain licensing plan, please see https://help.cloudasta.com/how-do-i-add-more-users-on-partial-domain-licensing-plan.
Important:
- You can only increase licenses during an annual commitment. You cannot decrease the number of licenses. However, you are allowed to reassign licenses to different users. (E.g. If you delete a user, you can use that same license for a new user.)
- If you prepay annually for Google Workspace, new licenses will be deducted from your prepaid balance and in some cases, we might reach out to you to add additional funds to cover costs of new user licenses.
When you're on an Annual Commitment billing plan, and you want to add one or several licenses to your account, you need to follow these steps:
- Access our billing portal (https://billing.cloudasta.com) and use your super admin user to log in.
- Click "Add more users."
Enter the number of user licenses you would like to add. So if you currently have 30 users and want to add 5 extra users, you need to enter "5", not "35"! 
Click "Continue" - You may now log into your Google Workspace domain control panel and create new users.