GS-911 firmware update available! Details at https://www.hexcode.co.za/november-2020-firmware-upgrades-available
Hexcode introduced enabling keys on some models in 2016 the news announcement is belowhttps://www.hexcode.co.za/december-2016-software-updates-availableYou would need to look at the function chart to see if your model is included https://www.hexcode.co.za/products/gs-911/function-chartor contact support at Hexcode to confirm https://www.hexcode.co.za/contact-us-1
While the function referred to by WayneC can enable and disable keys, it is not possible to program a new key, ie. one that does not have an existing code programmed.