Every timber floor will change colour over the years. Due to UV light exposure the coating will become more yellow and wood will get darker. Sadly, that is inevitable.
You can help by blocking your floor from direct sun or shifting your carpet or heavy furniture from time to time from one place to another.

The number one enemy of every timber floor is grit and dirt from outdoors. They can damage the surface like sand paper. Use matts at all exterior doors to help prevent sand, dust and grit from getting inside. Small rugs, or a runner carpet inside the door area can also be very useful.