Download the PVM - Pattern Viewer and Manager installer on your second (new PC), run it and at the end of the installation process type in your license key. If everything works according to plan, you can then go ahead and uninstall the tool from the other computer.
However, just so you know, it's very likely that removing the application from your old computer won't allow you to install PVM on a third device.
In case you run into any troubles, or you have additional questions regarding licensing, I recommend contacting the developers directly using this email address: support@digitalquilting.com