Each plan is permitted a certain number of unique "Admin" users. An "Admin" user is any person whom you've allocated to any of the following roles for one of your forms:
- "User Management"
- "Edit Form"
- "Full Data Access"
If your plan for example permits 5 "Admin" users, you can have up to 5 unique people granted admin related roles across your forms. The number of forms these 5 people can be "Admins" on is unrestricted.
A full description of what each of these roles are , is viewable here.