Lilyflower, the longest tamagotchi age I have known is 24, or maybe 32. My advice would be to keep your tamagotchi alive would be:
1: Don't leave it alone ever.
2:Keep it on pause when ur leaving it alone
3: If u want ur generations 2 continue, I suggest say yes 2 the matchmaker when she comes (that depends how many times u've said no) hope this helps :furawatchi: