If you decide to upgrade the subscription, the change is immediate and your card will be charged for the cost of the upgrade. When you choose to downgrade, your current plan will be active till the end of the paid period and then change to the chosen plan. Subscription upgrade or downgrade affects all users on the team, so when you switch to the Pro plan, all of them will be on it, but if you go back to the free plan, your whole organization will be limited to free features only. You can perform both of these actions by going to the Administration panel and in the Billing section, clicking on Plan. To upgrade click on Upgrade to Pro and choose your subscription details. To downgrade to a free plan or choose a different number of user seats, click on the ellipsis on the right side of the screen.