Invalid license?

David, Have a look @ this article (http://avgclick.me/1Jmbib9).
AVG Guru

I registered my copy of AVG late last year (2014) , license was accepted and system installed okay. Now I have started receiving desltop messages saying that my license is invalid, and that avg will cease in 28 days.
Why, as my license was iniatally accepted, has it suddenly become invalid?

David, Have a look @ this article (http://avgclick.me/1Jmbib9).
AVG Guru