Snails come and go. Their lifespan is pretty limited. This one is dead... his shell is at the bottom of my newest tank. To proliferate them you need a male and female and keep an inch of air above the water level. The female will lay the eggs stuck to the glass and the male will fertilize them. Than they will drop back into the water once they're fully incubated. They don't stand a chance in my current environment but I'm thinking of going all 120 gallons again... which gives them space from all the predatory little shits aka Plattys. (Plattys even eat the shell for some reason... must be nutritious)
I made the mistake of getting more than one and ended up with a tank full of baby snails that none of my fish could touch. My loaches loved to eat snail but these ones have that hard cap they can pull over the top of the gap in the shell that would stop them being eaten.
When did you get this snail? Is it the only one?