If you are using Grammarly Premium and experiencing the messages below:
Then, there are only two reasons for these two problems (of course).
  1. You are logged in on your Grammarly account inside your browser, or
  2. You are not allowing Grammarly to access all the sites in your browser.
For the tutorial of Grammarly is active, but key features are missing, visit here. And if your Grammarly is continuously logging out, then follow the tutorial below.

Note: This tutorial is for Google Chrome users:

1. Open your Chrome, and then type "chrome://extensions/" and then press the ENTER key.
2. Inside the Chrome Extension page, locate Grammarly.
3. Click Details.
4. Find Site Access.
5. There are three (3) choices there: On lick, On Specific sites, and On all sites. Select "On all sites."
6. Done!

Now, try to log in to your Grammarly account again, and the "You have been logged out. You are being redirected to the login page" will not appear again.

Honestly, I experienced this problem because I tried to use "On Specific sites," but when I tried setting it back to "On all sites," the problem is quickly solved.