The standard balls are indestructible, and you have an unlimited supply of them.
Balls you buy include a limited number of hits before they have to be taken out of play, and if hit OB, in the weeds, or in a water hazard and deemed 'lost', a purchased ball is also taken out of play immediately, regardless the number of hits that remained on the lost ball.
Of course, it's likely the computer program knows exactly where the 'lost' ball is.