Fatal error out of memory

As soon as I get more than 5 people on the website I get this message all the time and the site fails to load. http://www.esportsone.com

I heard there is a file you can add something too?

We contacted our server provider many times with this issue and they increased our memory on the server more than 3 times so it has plenty of memory.

Is there something in the theme code that can help

Here is an example of the error

Out of memory (allocated 1310720) (tried to allocate 3072 bytes) in /home/esportso/public_html/wp-includes/functions.php on line 2700