The jar of flour was not spent, neither did the jug of oil become empty, according to the word of the Lord that he spoke by Elijah.
1 Kings 17:16
Consider the faithfulness of divine love. It is clear that this woman had daily necessities. She had to feed her son and herself in a time of famine; and now, in addition, the prophet Elijah was also to be fed. But though the need was threefold, the supply was not spent, for it was constant. Each day she made withdrawals from the jar, but each day it remained the same.
You, dear reader, have daily necessities, and because they come so frequently, you are apt to fear that the jar of flour will one day be empty, and the jug of oil will fail you. Rest assured that, according to the Word of God, this shall not be the case. Each day, though it bring its trouble, it shall also bring its help; and though you should live longer than Methuselah, and your needs should be as many as the sands of the seashore, yet God's grace and mercy will last through all your necessities, and you will never know a real lack.
For three long years, in this widow's days, the heavens never saw a cloud, and the stars never wept a holy tear of dew upon the wicked earth: famine and desolation and death made the land a howling wilderness, but this woman was never hungry but always joyful in abundance. So it will be with you. You will see the sinner's hope perish, for he trusts in himself; you will see the proud Pharisee's confidence crumble, for he builds his hope upon the sand; you will even see your own plans blown apart, but you will discover that your daily needs are amply supplied. Better to have God for your guardian than the Bank of England for your possession. You might spend the wealth of the nations, but you can never exhaust the infinite mercies of God.
Taken from https://www.truthforlife.org/resources/daily-devotionals/02/28/0/