By default, every time you restart the license server, it overwrites the existing debug log file.
You can put the license server into “append” mode for logging, so that the log file isn’t cleared every time you restart the server.

To put the log into “append” mode, just add a plus sign (+) before the name of the file.

You won’t be able to View Log from LMTOOLS, but you can open the log file with your favorite text editor.