About a week ago, I started to see the above popup every time I started an Office application on my laptop. I followed the Go to My Account button, logged into my Microsoft Account and noticed that my renewal was unsuccessful since we changed our credit card.

I assumed (incorrectly) that if I renewed my subscription, this would fix the problem. I continued to receive the error every time I started an Office app. I was very frustrated.

I decided to take 15 minutes one afternoon and find a fix. A quick Google lead me to this blog post:

http://itgroove.net/kinglou/2016/02/19/stuck-in-office-365s-subscription-reactivate-account-loop/

The steps outlined above fixed my issue.