Starting April 11th, you won't be able to sign in to Mercury Mobile until you've installed the most recent update released on April 7th, 2015. But don't worry, just update the app like you do any other mobile apps you have on your device, and you'll be on your way.
If you have any questions, contact your vendor relations team by clicking "Contact Support" inside Mercury Network, or call 1-800-900-4954.