Perhaps the weirdness surrounding the QuickBooks licensing is part of the problem; I’ve seen this confusion prevent businesses from running their QuickBooks on remote systems simply because they could not figure out the right way to do it and still conform to licensing rules.
Consider that QuickBooks is essentially a single-user application, and it’s the database manager that really allows concurrent multi-user access to a data file. The program was not designed to have multiple users of the PROGRAM all running from one computer concurrently (which wasn’t a problem when only one person at a time used a computer). But these days, with terminal servers and remote desktop capabilities, a single computer is essentially turned into a box containing a bunch of user environments (call them desktops, sessions… whatever).
Each of these user environments (desktops/sessions) are running at the same time and on the same computer. So, when a user goes to launch QuickBooks and then open a QuickBooks company file, the database manager looks at the computer running the QuickBooks license and says “ok, you have a license to allow QB to access a data file with one user”. When the next user launches QuickBooks from that machine it will allow them to open the program, but if they try to connect to the same data file as the first user, guess what? QuickBooks database manager looks at the computer and license and sees the same single-user license number coming from the same computer.
A single-user license means only 1 user can access the company file concurrently (at the same time). So, if two or more people are on the same terminal server (remote desktop server), and are trying to access the same company data file concurrently, the QuickBooks license on their terminal server must be at a level that allows all of them to access the company file at the same time, e.g., a 2- or 3-user license. This is not intuitive.