All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
It appears from this Hadeeth that being protected from the devil extends to the evening for the one who says in the morning: "Laa 'Ilaaha 'Illa Allaahu Wahdahu La Shareeka Lahu, Lahul Mulku Wa Lahul Hamdu Wahuwa A'la Kulli Shay'iin Qadeer." [None has the right to be worshipped except Allaah, Alone, without partners, to Him belongs all sovereignty and praise and He is over all things Omnipotent], as the Prophet said: “It will be a protection for him from the devil that day until the evening.”
Al-Munaawi said: “i.e. until the evening comes.” An-Nawawi said in his commentary on Saheeh Muslim: “It is better for him to say it consecutively at the beginning of the day so that it will be a protection for him during this day.” This means that (by saying it,) he will only be protected during the day (i.e. until the evening).
However, there is another Hadeeth which means that whoever says "Laa 'Ilaaha 'Illa Allaahu Wahdahu La Shareeka Lahu, Lahul Mulku Wa Lahul Hamdu Wahuwa A'la Kulli Shay'iin Qadeer" in the morning 10 times he will be protected from the devil until the evening, and if he says it in the evening, he will be protected from the devil until the morning, and in this case, he will be protected for the entire day [by saying it in the morning and evening].
Abu Hurayrah said: The Prophet said: “Whoever says "Laa 'Ilaaha I'lla Allaahu Wahdahu La Shareeka Lahu, Lahul Mulku Wa Lahul Hamdu Wahuwa A'la Kulli Shay'iin Qadeer" ten times when he gets up in the morning, one hundred good deeds will be written for him, and one hundred of his sins will be lifted from him, and he will have reward equal to that of freeing a slave, and he will be protected (from the devil) on that day until the evening, and whoever says the same thing in the evening, he will get the same reward (as mentioned).”
Allaah Knows best.