To save an int in beteween rounds the best I can come up with is at the end of a round grant all players some item, like a plant or crystal. Go in the round settings device and set Keep items in between rounds.
WHen the new round starts use conditional buttons to check which item the player has.
This method only works if you want to save a small int, like <50. Because you would need 50 conditional buttons and 50 item granters for this