Why the battery of the laptop is not long lasting and replaced after using of 03 years?

You need to use it until it is almost empty then power it back up. No do it when it is at 80%.

If you use it a lot then it needs to replaced sooner.

Do you read spawn. Spawn has only a certain amount of magic units that he can use. Once he uses them all up, he dies. The same apply to the laptop battery. Every time you recharge, you’re using up your units. Recharge often then your battery dies sooner.

Mai is correct. Also, do not leave the charger connected after the battery reaches 100%.

Your computer may have software in it to manage charging, so that it will not charge before the battery is almost empty, and will not continue charging after the battery is full even if the laptop is left plugged in. However, not all laptops have such software, and those that do MUST be used with their proprietary charger in order for this automatic software to work. If you have replaced the charger with a generic one, that software does not work.