Paid Norton Security antivirus occassionally reverts to free version

Hello,

 

As the title suggests, every once in a while I will go to open the app and find that it has reverted to the Lite version with an option to upgrade. One time it went back on its own. The other day I tapped the upgrade button and it reverted to the paid version. Why is this happening?

 

Galaxy Nexus phone running stock Jelly Bean 4.2.2.

 

While this may not seem like a huge problem, I worry if I ever lose my phone or it gets stolen while in this condition I will not have to ability to remotely lock or track it.