As long as the parakeet is in good health and the pet parakeet is taken well care of then you can expect the pet parakeet to live up to 14 to 15 years.
The average lifespan of a pet parakeet is between 10 to 14 years and the healthier the parakeet the longer it will live but most parakeets don't live longer than 14 years.
Not taking care of the pet parakeet properly can shorten the parakeets lifespan by as much as 4 years so be sure to care for the pet parakeet properly and it will live up to 14 years or at least it should.
Although most parakeets live up to 14 years there is a type of parakeet known as the Monk Parakeet that can live as long as 20 years with proper care.