follow through (on a promise)

This means to do what you said you'd do, or do what you promised.

You can express what you're following through by using "follow through on ___":

Are you going to follow through on your promise?

You can express what the promise was using "(someone's) promise to ___"

I'm starting to think that she might not follow through on her promise to pay us back.

make a promise

In English, we can “promise” or we can “make a promise.” These are very similar in meaning. “Make a promise,” however, has a little more emphasis, and sounds a little more serious. 

When you marry someone, you make a promise to be there for them.

When you want to make a promise, you usually don’t say ‘I make a promise.’ You can just say ‘I promise’:

I promise, I won't laugh. Now show me the picture!

‘Make a promise’ is for talking about promises:

I made him a promise, and I intend to keep it.

Aren’t you going to (do something)?

When someone should do something, but it seems like they aren’t going to, you might say “Aren’t you going to ___?”

Aren’t you going to say thank you?

Aren’t you going to tell her we can’t come?

Although this phrase has the form of a question, it’s more of a command. You wouldn’t want to say this to anyone you don’t know well. It shows some disapproval and is rather direct.