Help with Jetpack Plugin

Hello everybody, i’m trying to active jetpack plugin to use header logo, but when i try active, wordpress give me this error:

Fatal error: Allowed memory size of 67108864 bytes exhausted (tried to allocate 24 bytes) in /home/storage/0/ce/c6/camilafigueiredo/public_html/wp-includes/pomo/entry.php on line 76

Then i acessed the “entry.php” and go to line 76:

$key = str_replace( array( "\r\n", "\r" ), "\n", $key );

The complete function is:

function key() {
		if ( null === $this->singular || '' === $this->singular ) return false;

		// Prepend context and EOT, like in MO files
		$key = !$this->context? $this->singular : $this->context.chr(4).$this->singular;
		// Standardize on \n line endings
		$key = str_replace( array( "\r\n", "\r" ), "\n", $key );

		return $key;
	}

But i’m don’t know what to do to put this plugin on, anyone can help me?