You don't -- if you do it won't work right. An installed copy of Final Draft is more than the program folder that's visible on your hard drive in Applications (Mac) or Program Files (Windows). A number of other crucial program components are installed to various places in the operating system and unless they're also copied to the target computer, the program won't have everything it needs to run properly.
You can put a fresh install of Final Draft on as many computers as you want so there's no need, ever, to copy an installation from (for example) your old computer to your new computer. Instead, use the installer. Full installers are available HERE (choose your operating system and your version of Final Draft.
You do want to move the activation off that computer to make it available for the other computer.