When you say "continuously", are you talking about every reload of amazon.com causes it to pop up?
Are you using Ccleaner or clearing history or something all the time?
I would say weekly, no ccleaner, just adblocker extension.
Also, I notice there's already an extension with a similar "a" on it in your picture - what is that?
That's exactly the extension Opera is pushing to install, it shows up with the pop-up, and disappear when clicking no.