confirmcheats command
Confirms that you accept cheating on this character. On a character that has never cheated, the first cheat command you run does nothing except print a confirmation prompt; confirmcheats answers it, and cheat commands work normally from then on. It also marks the profile as cheated, which is what stops achievements unlocking on it. Hidden from the help list.
Cheat commands need the console enabled with the -console launch option, then devcommands typed once. They work in singleplayer or when you host, not on dedicated servers.
Cheats are accepted on this character and the cheat commands start working.
The mark is permanent for that character. A world or an item flagged as cheated counts the same way, so a clean character can still be blocked by what it's carrying.