I love this tool! It helps me to compose emails that are grammatically correct and that give the tone that I want to give as well.
I love the insight report that comes in once a week as well. It gives me valuable information about the things I wrote the week prior.
I don't have proof of purchase because our office bought a license for the entire organization and I do not have access to that information, but I assure you, I use this tool every single day.