Try this link.
I think it'll answer the question.
Life Cycle of the Freshwater Snail | Animals - mom.me Life Cycle of the Freshwater Snail
I googled the question & this site answered the question spot on, but now I see the link opens "Life cycle" of snails...
Ok, try the one below -
How Long Do Aquarium Snails Live? | Animals - mom.me How Long Do Aquarium Snails Live?
The links don't list life expectancy by kind.
But it's interesting general info.
Endlers should be kept in groups of 6 or more because they're schooling fish. Assuming you have 6 of them plus a betta and shrimp I wouldn't add anything else as you're already a bit overstocked. If you have just the one endler then you could get a single apple snail- they need about 10g for 1 snail because they (like all snails) produce a whole lot of waste.