Also, I would like you to explain what you mean by "Even my own pics are limited to be thumbnailed in big size, when i posted all of them for public".

You should see your own pics in full size as well as pics of people who added you to their friends. This works for me, and there should not be any reason why it does not work for you. Other members or non-registered visitors, indeed, will see your pics reduced to 720 by long size.

Big pics are shown shrinked to the screen size, if they exceed its width, you have to click on resize bar above image to enlarge them. But this was so from the very beginning of this site. It has nothing to do with premium accounts.

This site was always a business. It's stated on the "about" page, actually. However this is as far as it gets. I will not make any further restrictions.