Can keychain remember ALL login info?

Is keychain able to remember all login info, like for 3rd party apps, an when you try to buy/install an app from the app store, and it asks for the password every time? or does it just fill passwords for websites in safari? I have some apps that require to enter password (they remember username only) every time you open it (even after being idle for a bit in multitasking tray)... such a pain.

Also, are there any 3rd party password manager apps that can remember login info including passwords for 3rd party apps and apples native apps like app store? I have used RoboForm for my computer (PC) for years and I love it on a computer, but not so great on iphone. I downloaded the free RoboForm app and it synched with my everywhere account and downloaded all current logins, but it doesn't work for apps like it does on a PC.