你的句子中的 its 为形容词性物主代词。its 用作形容词性物主代词和名词性物主代词的区别是：
1. 用作形容词性物主代词时，它后面必须接有被修饰的名词。如：
Beer is at its best when it is cool. 冷啤酒味道最好。
The baby is sucking its thumb. 这婴儿在吸吮拇指。
That place is well-known for its beautiful scenery. 该地方以风景美丽著称。
The verb agrees with its subject in number and person. 动词在数和人称上与主语一致。
Everybody is aware of its importance. 每个人都意识到了它的重要性。
2. 用作名词性物主代词时，它后面不能有被修饰的名词。但实际上 its 用作名词性物主代词的用法很少见，下面两句摘自张道真《现代英语用法词典》：
The cherry tree gives its share of colour to the garden, and the lilac tree gives its. (Eckersley)
History has its lessons and fiction has its. (Eckersley)