Reduced backlight after years of usage

Hi,

I have a MacBook Pro 17" (early 2009) and compared to my brother MacBook Pro 13" (mid 2012) mine appear to have poor backlight even at maximum light.

Does the backlight have a lifetime?

Did this mean that in some years I will need to purchase a new MacBook Pro since mine appear to loose backlight brightness year after year?

Thanks for the answers

Marcos