The game does not allow you to stop playing whenever you want.
"i don't believe this is intentional, but there is no manual save feature or autosave indicator and if you close or leave the game suddenly it tends to lose level progress, which encourages you to finish minigames and click around for a bit to guarantee your progress isn't lost"
"The game will keep moving forward whether you take part or not. There’s always artificial scarcity in that time."
"the order board refreshes every two minutes, so if you’re working on an urgent order you might not want to stop until it’s cleared"
"I don't remember if you can suspend a game in progress if you know you're not going to be able to interact with it that day, but I don't think you can."
"Since matches are online versus other players you cannot pause the game while you are in a match (which is fair though)."
"You can pause the game whenever you want but you can't save your progress mid-day (in-game days are the game levels). You have to restart that in-game day's orders if you quit part of the way through."
"its an online multiplayer game where you can't really pause unless in a custom match. You also cannot save your game progress in the middle."