Checking the time stamp of the TKST.UD file located in the C:\Program Files\United Devices folder is a good indicator of when the agent last saved its results.
This file is updated every time the current work unit (WU) finishes a molecule. Looking at the work unit screen (by clicking on the "I" button) you will see a current molecule: indicator in the upper left corner. The last two numbers of this display indicate progress. When this number reaches 100 and starts over from 1, a molecule has completed, and the TKST.UD file will be updated. With some WUs, this happens several times within each percentage point on the progress bar.

If you're waiting to halt the WU to restart your computer or for some other reason, you can do so at this point.
To do this, first minimize the UD screen by clicking the down arrow, lower right corner. Then right-click on the blue UD pill icon in your system tray. In the pop-up menu, click "exit". This stops the program, and at this point you can reboot your machine or perform other tasks such as defrag. When you reboot or restart the Agent, the blue UD pill icon will appear in your system tray again, and the WU will have restarted. If you have not rebooted, simply go to the START button, PROGRAMS, STARTUP folder, and click on UD AGENT. The program will restart at the percentage point that was saved, and you will not have lost your work.