Thanks, that's a relief. I had read that the kibble of life could only be used one time.
I play my sims almost in "real time." As in, I've had the game for two years, so the sims have been alive two years. Having a pet die after a month of play doesn't make sense with that mindset.
I play very similar, my sims are aging very very slowly. One good idea of Pets was that they age at a different time (between 10 - 12 a.m., I haven't completely worked it out, because I always forget to check at the right time), so it means you can turn aging off in the morning and turn it on again afterwards if you want your "human" sims to age.