If someone leaves your organisation you have the option of reassigning their spot to a new member. Each member has their own login details and all their property data will be saved under their profile.
In the main menu go to "Manage" >> Groups
Remove the member who no longer is part of your team by selecting the trash can "Remove Member" option next to their name. You will now have an available membership subscription for the new member.
Invite the new member to your team using the "+ Invite Member" button next to your team name. Their invitation will remain pending until they have accepted the email invite and logged in. *Wait at least 15-minutes before inviting the new team member to allow time for the subscription system to sync and update your account.
If you're adding multiple new members to your team you will have to update your subscription.
*Refer to this Help Doc on Updating your Subscription