Some have mentioned that logging in and ticking "Remember for 30 days" solves the issue (for 30 days, I guess). The wrinkle is that if you click on the extension icon and it requires you to log-in again, it doesn't take you to a log-in page with the 30 days option. You actually need to ignore that log-in page, and go to the standard sign-in page you can get to from Evernote's website header. That seemed to solve the issue for me for having to log-in repeatedly.