Generation 7, back on my v1. I could totally do more, up to 99, if I was interested enough in doing so. I've never let a Tamagotchi die on me without having a baby first.
mine was 33! on my light blue version one with yellow buttons. but then one day i was practicing cartwheels on my lawn and mt tam was sitting on our letterbox...i finished a triple cartwheel and she was gone. so sad i dont know who stole her...i looked high and low for ages. her name was delta and she was hinotamatchi. *sob*