memory_limit is by default set to 1024MB for all web hotels.
You can set memory_limit on your own. If you need more memory, you should check first if the cause of the memory problem is not an error in your code, database or other similar, and not just because memory_limit is showing 'too low' - as this is often not the case.
memory_limit can be freely adjusted through .htaccess or directly through the PHP code ini_set()
Some CMS (eg WordPress) sets their own memory_limit and memory_limit must be set in a special way. See the documentation for the CMS you are using.