The every tick is under system. You want the pacman to always move, so you will need every tick. I think you don't need a boolean.
If the user hits a key you can change the direction pacman is facing and/or moving. You can either use a variable for this and ask if this variable is 1, 2, 3 or 4 (for each direction). You can also safe "left", "right", "up", "down" instead in this variable. Or you can just change the direction pacman is facing and ask which direction he is looking.