In addition to variables, you can use flags to keep track of where the player has been in the story. To set a flag, just use the gain command.
In the first example, there was a command, gain MET_ROBET_FROST. This enables the game to remember which choice the player made. MET_ROBERT_FROST is a “flag” that the player has earned, and your script can check for its existence later in the story. You can create any flag you like.