Acrobat Pro XI always ask me to sign in to supposedly "trial software" - never happened before

Hello there,

I bought the Acrobat Pro XI last year and had a license but just today, when I try and click to view a PDF, my Acrobat XI Pro now ask me to Sign In.

"Please sign in with your Adobe ID to use your trial of Adobe XI Pro"

It's claiming that I am using a "Trial" version which is not correct.

Why is this happening?

Thanks