How long does a Tamagotchi live?

I have been taking care of my sons Tamagotchi's , (he got bored with them) And one of them is already in its 5th gen. but the other one has never gotten married or had a baby. I just take care of her and feed her , play games with her and she still hasnt died. She is 32 years and 99 lbs. She definetly is old , she is wrinkly....lol