1. Someone can work on the database on the hosting computer. Purists would recommend against it, but Filemaker allows it.
2. One Filemaker copy on one computer opening a database or mulitple databases counts as one user. to the hosting Filemaker application.
If you have two copies of filemaker on a computer (FMP ver 8 and FMP ver 11) and they both open a hosted database they are two users.
If the same copy of Filemaker is on two computers, the second one will refuse to open until the first is closed or computer disconnected from the network.
Thank you that clears my concern.