Refrigerator lights are made to last a long time. If yours keep burning out, please see if one of the following will solve the problem.
Your refrigerator's internal light bulb should go out when the door is closed. If, for some reason the door doesn't close completely, the bulb may stay lit, which in turn causes it to burn out faster.
Check to see if there are gaps between the door seal and the cabinet. If you find any, adjust the door seal by gently pulling away from the door using your fingers. For any openings that persist, you may need to replace the seal. In that case, contact an authorised service agent.