Use an optically-isolated OC4USB cable. The driver usually installs automatically when you first connect it to your PC.
FlukeView 2 often uses a (tied to one machine). If you switch computers, you must deactivate the license first: flukeview 2 activation key
If you need a valid key, here are the only reliable paths: Use an optically-isolated OC4USB cable
Ensure you have the latest version (currently v3.2.0) from the official Fluke Software Downloads Open the Activation Dialog: When you launch the software, an Activation dialog box will automatically appear. Enter the Key: Carefully type your 15-digit activation key into the field. Click Activate: flukeview 2 activation key