When your potted lily comes into bloom, not all the buds will bloom at the same time. This naturally extends the flowering time of your lily, but you will have to maintain the lily during flowering. Not only by ensuring that the soil remains sufficiently moist and that it is placed in a spot with half sun/half shade, but also by cutting faded flowers from the plant. This not only makes new flowers stand out better, but it also prevents annoyances about unsightly faded flowers, falling petals and pollen.
Do you want to plant your potted lily in the garden after flowering, so that it blooms again next year? Then make sure that the last flowers are also cut away when they have finished blooming. If you don’t do this, the plant will produce seed buds. If you do and let the plant die in the autumn, the bulb will remain in the ground and will gain new energy in the winter to grow and bloom again in the spring.