Is 1Password logging me out of websites after a certain time?

It varies. Often I'll put my Mac to sleep at night then in the morning, come on and find that some websites have logged me out. Not every morning, but more often than not. Sometimes I can be logged out within a matter of hours or even within an hour. Sometimes I can remain logged in for a few days. And this isn't all websites - usually ebay and Amazon, and a few others.

What you said about session cookies is interesting, as it might explain why only certain websites do this, with others perhaps using different cookie time limits. That might very well explain what's going on. I think I'll shift my investigations to my internet connection. It's quite possible that my ISP is rolling out upgrades or doing some work overnight, resulting in a brief interruption of service. That would explain the 'next day log in again' thing.

Thanks for your thoughts.