Should you choose to change your PC, the application must be uninstalled from the old machine.
During the uninstallation process, a dialog will open asking you whether you want to deactivate the software in order to use it on another machine. If you choose yes, you can install the software again on another machine and activate it by using the same license key.
Please note that the deactivation requires an active internet connection and no firewall or proxy that can prevent the communication.