The expected life expectancy of a bulb during typical operating conditions is more than 2 years, but may be broken, for example, due to a drop of the device.
By purchasing a replacement bulb, in such a situation, you can simply switch to a new one and continue to use without painful breaks and waiting.
exchange instructions in more detail:
first remove the protective element of the heating element. It's just set in a small groove inside the tube and leaves quite a bit when you press it down slightly from one edge and then lift it off. It is not advisable to destroy it when it is nice to put it back after replacing the bulb.
Then there is a bulb inside the tube. It's just by pressing its position. it is good to have some hooked tool that can bring the old bulb between the legs of the bulb leaving it intact. I actually use a crochet hook, it works fine there, but other solutions probably exist