The leather was treated minimally against stains and grease the first time, but aniline leather remains subject to air and sunlight because it is colored in the pores.
In any case it is best to protect the leather extra against stains and grease. You do this by evenly rubbing it with a colorless leather treatment 2 to 3 times a year. You can easily find these products online or in do-it-yourself stores.
Note that the treatment preserves the suppleness of the leather and reduces grease absorption by the leather, but does not restore color.
As with all 100% leather products, signs of use will develop over time which will give the leather a more lived-in look. This color evolution is typical of aniline leather.