Promise is a noun and a verb.
A promise is something that you say you will definitely do:
I’ll be here for your birthday. That’s a promise!
We often use the verb make with promise:
Beth made a promise to Owen that she would look after his dog whenever he was away. Now she regrets it.
We can use the verb promise to say that we will definitely do something. We use it with a clause with will, would or with a to-infinitive. It is sometimes followed by that:
I promise I’ll buy you another one.
I promise I buy you another one.
I promise never to tell him.
The builder promised that he would be here on Tuesday.
We can use the modal verb will to make promises:
I’ll always remember you.
We’ll send you the contract tomorrow.