Each ball can only be used for a limited number of shots. The number of hits will be tracked and displayed on the swing interface in the game under the HITS meter. This will give you an estimate of how many hits you have left with that ball. Putts are not counted as a hit to the ball unless the putt is a mulligan. If it is a mulligan then two hits will be deducted from the durability.
When you have 25% durability left on your ball, the HITS meter will turn red.
When you reach the hit limit for the ball you are using it will be replaced automatically with a new ball of the same type and color. If you do not have any more of the ball type and color in your inventory then the Basic ball will be inserted. The Basic ball is the ball provided to you when you first start playing WGT. Once you play with the Basic ball you cannot change balls during your round.
If you hit a ball OB or into a Water Hazard that ball will be removed and will be replaced with a new ball of the same type and color if you have one. If not, it will be replaced with the Basic ball.
A message will be displayed when the ball you were using has been taken out of play and replaced.
Yes, you can visit the Pro Shop during your round to replenish the ball you are using. If you lose your last ball of a specific type and color you can purchase new ones in the Pro Shop but will not be able to use them in your current round if you have already switched to the Basic ball.