Three ways to run it. They're the same app and the same licence key — pick whichever suits how you work.
Everything happens on your own machine — your artwork is never uploaded anywhere. Works offline once it's loaded.
Gives you a proper window with its own icon in the Start menu or Dock, no browser chrome, and it keeps working with no internet. Same app, one click, nothing to download.
Checking whether your browser can install it…
The one extra thing this does: it finds your machine's USB drive by itself, so you can send a design straight to it without hunting for the drive letter. Worth it if you're sending files to the machine all day.
Each version keeps its own licence. If you use both the browser and the desktop app, paste the key into both — that's expected, not a second purchase. A one-off key works offline forever and never checks in with a server.