LiPo batteries will not work forever, the number of charge cycles & time it can show a healthy performance depends on a number of thing's ... but mainly how it has been stored & how old it is. But eventually it will fail & can't keep your drone airborne.
LiPo batteries don't like to be fully charged, try to minimize the time they are 100% by charge them up just before you use them (the day you fly or evening before). Don't recharge until cooled down to room temperature. Once used down to minimum 15-30% & before storage, charge them up to 40-60%.
All LiPo battery cells allowed to go under 3V sustain permanent damage ... so your battery shall be grounded from now, buy a new.
The only way to see the "end of life" coming for a battery, in time before you have a cell failure is to monitor the battery behavior over time. Follow maximum flight time, cell deviations & abnormal voltage drops & when deviations & voltage drops starts to happen on regular basis take it off flight duty & only use it for desk duty to set drone parameters, unload pictures and vids ...
I have monitored one of my batteries due to a constant bad behavior when using Sport mode & when it was cooler weather ... recently I had a large voltage drop from start in Sport mode in 25C degrees ... that battery is now grounded & I have bought a new one.
Airdata.com have a paid subscription that provide trends from all your uploaded flights there ... those trends will give you means to take a decision about a battery ... well worth the subscription fee, it's a kind of insurance that will save you the coming cell failure once you are airborne.
This is the trend for that battery from Airdata.com ... have multiple large cell deviations (purple bars) & minutes per battery goes down ...
And this is from the flight that made me ground it ... note the severe voltage drop down to 3,167V 42sec into the flight, just a tad more & my drone had started to autoland.
