Most small lasers of the type used in A/V equipment are rated in terms of hours of use -- as an example, 5000 hours. That figure, however, is at best a SWAG, since the laser may fail sooner or substantially later. The lifespan of the laser can ber affected by a number of factors, such as how well the internal power supply is regulated (avoiding power spikes is important), the amount of heat the player is subjected to, etc.
I had an Adcom GCD-575 that worked for more than 6 years of fairly frequent use before the laser failed. I suspect that Sean can give us more accurate info, assuming he sees this post.