You can add users yourself under User Management in your Settings view. Once you add them we’ll make a one-time, prorated charge to cover your new team member’s account for the remainder of your current billing period. Then you'll be billed the new amount on your usual billing date going forward.
As an example, suppose your team is subscribed to the “Advanced Planning” module, which costs $6 USD per user per month when billed monthly. You add a new team member 10 days into your billing period and there are 20 remaining days in the month. The per-day cost for each user is $6 USD / 30, so we will make a one-time charge of $4 USD ($6 USD / 30 days * 20 days) to your payment method on file in your account.