Display content only on first visit, after 2 hours expires display it again

I have three parts of code (content) on my WordPress website included into [login to view URL] file. One code is included for page #53, one code for page #51 and one code for all other pages. This is how I made it: <?php if(is_page() && !is_page(array('51', '53'))): ?> FIRST CODE <?php endif; ?> <?php if(is_page('51')): ?> SECOND CODE <?php endif; ?> <?php if(is_page('51')): ?> THIRD CODE <?php endif; ?> Now I need to display first content (code) to visitors only on their first visit. After that they shouldn't be able to see the same content for the next two hours. After two hours they can see it again. I think that can be done with PHP session and cookies. For someone who knows PHP this is one working hour. I will pay you 10$ if you can do it till friday 02.05.2014.