Jasem is certainly a better authority, but the short answer is Yes, you can update SM without resorting to a key. By a "key" I assume you mean downloading a version onto a thumb drive and flashing the small card that plugs-into the SM.
For example, Linux distributions often update the kernel with the updates installed via a program like apt or yum. The same holds true for updating the Rasberry Pi OS. Updates to Ekos are on a bi-monthly basis and I doubt it's expected we would all go flash new cards every two months.