I just got an email from ProWritingAid that prices for all subscriptions (1-year, 2-year, 3-year, and lifetime) are going up 20% on January 1. I’m not sure what timezone they’re marking the New Year with, but they’re based in the UK, so if you want the cheaper price, I’d get it now.
I am a ProWritingAid affiliate and after Thanksgiving, they gave me a 25% off coupon to share, so feel free to stack that on top if you decide to subscribe. The coupon code is LOWRY25 and the link to use is http://prowritingaid.com/?afid=4421.
Oh, and even though they are based in the UK, they are also excellent at American English. This is the main copyediting software I use; you can read more about it in my post Four Easy Online Editing Tools for Writers.