With this particular bulb, you get a lifespan of about 8 000 hours. This particular model has a so-called G5 socket, so make doubly sure that it will fit.
From Amazon
Osram 13 Watt Lumilux Basic T5 Short Fluorescent Tube Lamps
LED Bulbs
Osram T5 Fluorescent Tube 13W 517mm 20 Inch Cool White - 008974
Big on Electricals
Osram T5 Fluorescent Tube 13W 517mm 20 Inch Cool White - 008974