The latest version of Semaphor for Windows, macOS, and Linux is always available at https://spideroak.com/semaphor/download/.
To check to see if Semaphor is up to date, desktop users can do the following:
On macOS, go to the Semaphor menu and select "Check for Updates...".
On Linux or Windows, select the Tools option from the menu bar at the top of Semaphor's application window then select the "Check for Updates…" option from the dropdown menu.
This will open a new browser window to report whether your version of Semaphor is the latest release. If the version you are running is out-of-date, it will provide you with a download link to the current version.
If you are trying to update through a mobile device, simply open the Semaphor app page through your device's App or Play store and update as you would normally.