Is it purely medicine or is a big part of that living conditions?
I guess it is a bit more nuanced than I formulated in my original comment. If your cat is healthy and dies of some kidney disease it is completely OK to heal that cat, in my opinion.
I just don’t think a cat, as it stands now, is made to live to 30 years because of cell decay etc.
In my time I have seen people keep other beings in a miserable state just because they couldn’t let go. They pump them full with medicine, not because they have a better life this way, but because they can’t let go.
And those beings where completely helpless and suffering. That is just something I don’t wish for a innocent being.