keep a promise
keep one's promise

He had to plan some way in which to keep his promise.

She wanted very much to be good and to keep her promise.

You got him for me, and I have kept my promise.

So he had kept his promise, and let me go.

But I have to keep my promise to myself, too.

I was not going to keep my promise to you.

Seems I kept my promise and brought you up here.

And look what happened to them, because he wasn't man enough to keep his promise.

A girl who could help him keep his promise about the future.

She might yet be given a chance to keep her promise.