How do you change finally into a noun?

You can't directly change "finally" into a noun. It's an adverb, meaning it describes a verb.

Here are some ways to use a related noun:

* Use a synonym:

* End: "The end of the long journey was in sight."

* Conclusion: "They reached the conclusion of their investigation."

* Resolution: "We finally found a resolution to the problem."

* Use a phrase:

* The final moment: "The final moment of the game was filled with tension."

* The final outcome: "The final outcome of the election was uncertain."

* Use a different construction:

* "It's finally done!" can be changed to "The completion is finally here!"

Remember, the specific noun you choose will depend on the context of your sentence.