If any lights bulbs continuously burn out faster than their specified lifespan, then look for the following:

- Are they getting too hot?

- Is their a short circuit?

- Is the connection arcing?

Could be that you have purchased a very cheap brand which is unreliable.

It may be that your house is experiencing voltage fluctuations for some reason.

Also if your lights have moisture in them, that will definitely shorten ten lifetime of the bulbs.

Note that the rated lifespan of a light bulb is its AVERAGE lifetime, under ideal conditions. So (a) some light bulbs will perform under the average and (b) your appliances may not provide the light bulbs ideal conditions.

If the light bulbs are installed in an area with no air circulation or where the insulation abuts the light too closely, they will get hot and die a quick death. LEDs cannot handle heat.

Most likely the reason is overheating. 

LED light bulbs are extremely sensitive to heat, and use heatsinks to draw that heat away. If that is compromised in any way it will degrade your light bulbs.

The other thing is that moisture can cause arcing and degrade the LED light bulbs as well.