When you run the TReK Assistant, cache files will be stored in the following location:

Windows: C:\Users\<username>\AppData\Local\gov.nasa.msfc.trek

Linux: /home/<username>/.local/share/gov.nasa.msfc.trek

The cache files are used to store information needed to support the TReK Assistant. In general there is nothing you need to do with this directory. However, if you ever find the TReK Assistant behaving oddly, you can try deleting the gov.nasa.msfc.trek folder to see if this fixes the problem.