One license of RW is good for up to 5 machines now, I believe. Before it used to be 2, so you’d still be covered.
You can also select a custom/external addons folder (e.g.: dropbox) and store your project files there as well, which makes swapping between two machines easier. You just have to be careful to close out your files when you’re finished so you don’t open the same file on different machines.