In order to move your already registered Tiff Viewer to another computer, please first make sure that you have a transferable license based on the description of How do I know if I have transferable license?
1. To move the already registered Tiff Viewer to another computer, uninstall the product from Control Panel on the computer to free up your license for use on a new computer.
2. When the uninstallation is complete, install the Tiff Viewer on the new computer and register with your existing serial number.