ETERNAL INHERITANCE

Christ shed His blood and became the mediator of the new covenant so "those who are called may receive the promise of the eternal inheritance"
Hebrew 9:15

What God promised isn't just for today; it is for eternity. That's why it is an eternal inheritance. The writer of Hebrews compares the new covenant to last will and testament.
  For where is testament, there must also of necessity be the death of the testator. For a testament is in force after men are dead, since it has no power at all while the testator lives (Heb. 9: 16-17).
In other words, the death of Jesus Christ activated the power of the blood that guaranteed our inheritance.
Some people have the idea that when we enter the kingdom of God, the Lord is going to judge us according to how we have lived, give us a mansion of gold, and that's it. No. The Bible says our inheritance is eternal, meaning it's an on going possession. When one reward is presented, I believe there will be another. It will be like a Christmas that never ends. Scripture tells us that "eye has not seen, nor ear heard, nor have entered into the heart of man the things which God has prepared for those who love Him" (1Cor.2:9). Peter says it is "inheritance incorruptible and undefiled and that does not fade away, reserved in heaven for you" (1 Peter.1:4). I am anxious to get to glory and find out what is in store for us.
The promises of God's Word. . .  both the Old and New Testaments be ours when we are redeemed by the blood
And if you are Christ's then you are Abraham's seed, and heirs according to the promise (Gal.3:29).
We don't deserve an inheritance because of our work of righteousness, "but according to His mercy He save us that having been justified by His grace we should become heirs according to the hope of eternal life" (Titus 3: 4,7). Too many people fear that they'll never see their inheritance. That must be because they don't understand God' amazing grace.