From Greenview Wiki
Once logged in to the control panel as an "IT Admin" account (or an account with similar permissions) you can modify your products, billing period, number of users, and add domains by following these steps:
1. Under "Client Account" click "Subscriptions"
On this page you can see your current products, cost, options (by hovering your mouse over the option in question), and total cost.
2. Click "Add/Edit Subscriptions"
On this page you can select the product(s) you wish to add or edit, and supply the information necessary for each product (number of users, etc.). You can also modify your billing period from monthly to yearly or vice versa.
3. Click "Sign Up!" at the bottom to save your changes
Each product will have additional steps in order to become active. You can find more information about your new product(s) in our wiki or you can always contact our 24/7/365 support department via phone, email or ticket from within your control panel.