The simplest way to achieve this would be to reinstall Dragon NaturallySpeaking 12.5 on the new computer, but not before you uninstall it from the previous one. This allows you to have the same license for the same application, but on different computer.
Before uninstalling, export the data and everything you might have added in Dragon NaturallySpeaking and then reinstall it.
It won't work with a simple Copy and Move procedure, because Dragon NaturallySpeaking is a very complicated application that requires advanced configuration which can only be done by its installer, that's why it's recommend to simply reinstall it.
If you purchased the application from its official website in digital form, then the license key to activate the program is in your email.