# Billing
Most Trello power-ups are designed to charge you for each user of your workspace or boards, regardless of how many people on your team are actively using that power-up. At Assista, we believe you should only be billed for what you use. When you purchase a paid plan for your Trello workspace, you will only be billed for the active members that use it, which you fully control.
To see all information about your plan and members, go to your Payments page (opens new window)
# How you are billed for members
If you’re on a paid plan and activate new members partway through the billing period, we’ll count the new members as "active" for the period, and bill you for them (prorated) if you don't have empty seats in your workspace.
# Example
You are on the Professional plan and you are paying monthly at $5.00 per member. Fifteen days into your billing period, you add a new member by activating them in the Manage Members page. At midnight UTC on the day after the activation, we will count this new member as being "active" for your plan and charge you (prorated) for them. To calculate the prorated cost for adding a new member we'd divide the cost per member by the number of days in the month, then multiply by the remaining days in the month. ($5.00 ÷ 30 days) x (15 days) = $2.50
# How deactivated members affect billing
You are only billed for the activated members in your workspace. If you deactivate a member halfway through your billing period, we will add an empty seat for your workspace for that billing period.
# Example
You are on the Professional plan and you are paying monthly at $5.00 per member. Fifteen days into your billing period, you deactivate a member in the Manage Members page. There are 15 days remaining in your monthly billing period. We will assign a new empty seat as credit for your account. You can use this credit to activate one additional member free of charge during the remaining billing period.