Why does gmail sign me out of my account every time I close my safari app on my iphone?

This is a recent development and I'm starting to get really irritated. It started happening today after I cleared my history. Before today, I could close all my apps and when I opened them I would still be logged into my gmail account. This is no longer the case, and I'm not sure why. I cleared my cache and enabled cookies, so I don't understand why gmail is doing this. I've probably tried logging into my gmail account 10 times trying to fix this.

You have deleted the previous cookie that validated the auto-login.

You need to use the "remember me" option when you sign in, to replace that cookie.

If you have set any kind of auto-cleanup in the web browser or any add-on to that, it may be deleting the cookie again each time you exit the browser.

Cookies are working while your browser is running or you would not be able to log in to any web sites - but that's a different thing to auto-cleanup or privacy settings that remove history when you shut it down.