if you use a battery in a particular way regularly
.... say 10 shots ... and then recharge it before taking 10 more shots - and do that every day - the older rechargeables would "remember" that ... and soon you'd only ever be able to take 10 shots before the batt stopped supplying juce.
in your case the battery has for whatever reason packed up
with moderate use ... not a lemon ... just how it happened ...
there is no "life" for a battery - the popular misconception is 1000 charges - but it depends on charge current, use, time stored ... charge state when stored ... etc etc ....
laptops guarantee = 12 months
.... except the battery - which is often covered by a different rule.
the simplest "rule" is when it stops working it's time to get a replacement