Looking for a free alternative to Microsoft Word.

Can anyone recommend a Word-processing application that can be downloaded? I've had Word for years. Back in the day, it used to come on Pcs. Then I purchased a product key to be used on my computer. I can't even phantom the thought of paying a yearly or monthly subscription for it. After moving to different cities and years passed, I lost the product key and I have a different computer than what I installed it on. I don't want to use the online word processors because I am having internet issues (which is completely another issue in itself). I really need to get started on finishing a book I started writing.

Are there any suggestions? Thanks in advance.