Go to Help > About Snagit > Support Information and scroll down to the "Registration Key".
If you cannot open the software, the key may still be stored in your system files or registry. how to find my snagit license key exclusive
He turned to the internet, searching for a backdoor, a master key, a list of exclusive license keys floating on the dark corners of forums. He found threads from 2014, cryptic pastebin links, and promises of "generators." Go to Help > About Snagit > Support