You fan add a Boolean named Stopped (for example) to an object
Every 0,03 seconded: add 1 to score
Is not Stopped
If WINNING = SCORE : Set Stopped to true
With this, when it will do the event, it will set the Boolean to true. There is a condition on the add 1 to score that will not be fulled. So it won't do it If you want it back, just do a Set Stopped to false and it will restart