Yes.
When you purchase any Surreal Machines plugin, you receive one serial and two download links. One link is for Windows, one link is for macOS. You can download both and install on different operating systems with the same serial.
You can download your plugins at any time by signing into your account on the Surreal Machines website where your available download links are listed. If you purchased from Plugin Boutique your serials and downloads are similarly available at your account with them.