I can't buy pro features. When i pay it show me this noti. But my apple id don't have any problems, i can pay app normally. Can you help me to fix?
Do you have any parental restrictions set? I'm just checking, since there are restrictions on 1Password because it has in internal web browser, and Apple imposes parental restriction on all web browsers. Also, I see that there is an iTunes web address to which you are directed for assistance. What happens when you go there?
I'll add that the buying process on Apple's App Stores is controlled by Apple, not AgileBits. That isn't to say that someone from AgileBits can't help you; they might be able to, but it would be based on their knowledge about how the process works, not their ability to intervene.
I've also personally experienced this error before and unfortunately the only way I was able to resolve it was to contact Apple support using the link they've provided in their error message. For me the problem was I had made a number of purchases in quick succession, and they wanted to verify that it was actually me making the purchases. A bit of fraud prevention, I suppose, which I can't fault them for. Unfortunately I wouldn't have any way of knowing what the specific issue is in this case, as what @hawkmoth says is true: the entire purchasing process is run by Apple, not by us.
Please let us know how it turns out!