The 'protection key' is your USB key plug (dongle). Could it be that you have a damaged USB port or that the keyplug itself is damaged? (A friend stepped on his and the metal connector was loose and only worked if you pushed on it. He has since replaced it.)
ArchiCAD checks for the keyplug during startup and periodically while running.
One of the forum moderators • AC 26 USA and earlier • macOS Ventura 13.2.1, iMac Pro 10-Core, Radeon Pro Vega 64