God Is Not Ungrateful
For God is not unjust so as to forget your work and the love which you have shown toward His name, in having ministered and in still ministering to the saints.
It matters to God if you minister to the saints and He won't forget what you do. The phrase ministering to the saints is a broad term; it could mean many different things. For instance, my sister used to take her kids to the elderly care facilities and they would spend time there just talking to the elderly. It could be giving money to missions for various things. Sometimes the greatest thing you give someone is a phone call if you say the right things. It could be anything you do for Him. But God is not like people. He is not ungrateful. People have a tendency to not remember what you did for them.
I'm sure we can all think of cases where we did something for somebody and after a while they didn't even remember it. They maybe even said out of their own mouth that without your help they wouldn't have made it, but then after a while it's not so important anymore. God is not like this; He will not forget. You'd be amazed at what He's like. He remembers the littlest thing that you do for Him. He's not unjust so as to forget. Seek Him while He may be found and when you're facing something He won't forget what you've done for Him.
Now I need to say this: You didn't buy anything from God. If you do anything for God and you are expecting to get something later, you have violated a Scripture. You shouldn't expect anything. He said lend expecting nothing in return. God will bless you. It's His own words but you can't think "well I did this for God so now He has to do this for me". He doesn't have to, but He wants to.
If you sow in love then you will reap in love. You who have been faithful can expect God to honor what you've done. He will do it. If you've done on a basis of just loving Him then you can stand there if faith. But if you've done it because you thought you were buying something or doing it because you wanted to receive something at the time you were doing it, then you will get nothing.
Hebrews 10:23 - Let us hold fast the confession of our hope without wavering, for He who promised is faithful.
And verse 35:
Therefore, do not throw away your confidence, which has a great reward.
The devil tries to destroy your confidence in God because he knows it works. He can use trials or just time because most of what you believe for does not show up in a day. We know what Ecclesiastes says, "Cast your bread on the surface of the waters, for you will find it after many days." Not tomorrow, not immediately, but after many days. Time has a way of eroding your confidence if you let it. But we can look at Abraham and see that the Bible says he grew stronger in faith and you can too.
God will not forget what you've done for Him. He is a very grateful God.