I installed Grammarly on my iPad after seeing the ad on YouTube, but then it took me to a permissions area under the Settings and wanted FULL ACCESS TO EVERYTHING. It won't work without the full access.
I'm an author and I really don't want anybody having access to novels that are yet to be released, nor the outlines for other novels. They're something that I don't want stolen or distributed about the internet before they're published.
The permissions for Grammarly say that they want full access to anything you write, or have already written. Basically, everything you type on your device goes to them. That's on the free version and is quite frankly a very scary prospect. I instantly uninstalled it.
Although they say they won't take credit card details, reviews deny that claim and I can't see how they'd be able to take one lot of your data and not all of it. Really think before installing this program and just how much of your private life they're taking through the data on your device.