Find what files a program is using

Solution 1:

You can use Process Explorer's handle viewer (View->Lower Pane View->Handles) to see all of the files a process has open on a Windows machine.

Solution 2:

As another answer suggests process explorer will show you currently open file handles for a process. (It is absolutely one of the best tools out there.)

If that is not enough, Process Monitor will show you a complete log of all file and registry operations that a process performs. That might help if you find you've missed something (like a registry key) after moving it.

It sounds like the software you are using is not very friendly. Let the developer know that you will be looking at alternatives if they won't provide an export feature.

Solution 3:

Process Hacker is very similar to Process Explorer and is also free, but this one is open-source. It equally let you find which files are being used by a process.

Solution 4:

Process Explorer is good, but it only shows you what is currently running, a library might just be used for initialization and then discarded or only used during some obscure time. Dependency Walker might be what you're after.