ListPro's data is stored only on your device, and backed up into the iTunes backup along with everything else on your device. If you are only using Mac OS X, you can still manually back up your data, but you won't be able to access it on the Mac.

To back it up from the device:

1. Start ListPro on your iPhone and back up to the home view
   
2. Press the sync button at the bottom of the screen
   
3. Touch the "Welcome.." text and drag it quickly downwards. You will see the screen switch to File Transfer Mode.
   
4. On your Mac, click on a Finder window, then go to the Go -> Connect to Server menu item.
   
5. Type in the "Address" shown on your iPhone and click Connect.   Use this format:  FTP://xxx.xxx.xxx.xxx:49050 with the IP address in place of the x's.
   
6. Enter the "Name" and "Password" shown on your phone's screen and click "Connect".
   
7. A Finder window will open, showing the files that are stored on your phone. Copy them to a folder on your Mac.

To transfer your data back, you can email yourself the .CLF files as file attachments, and then open them in ListPro on the iPhone using the Mail app.

If you are familiar with third-party FTP software, you can use any FTP program to transfer your files back and forth. You cannot use the Finder to transfer files to your iPhone.