Who:
preg_match_all('/You\'ve made a purchase from\s(.*?)\son Google Play/', $input_lines, $output_array);

Order code:
preg_match_all('/Order number:\s([A-Z]+\.[0-9]+\-[0-9]+\-[0-9]+\-[0-9]+)/', $input_lines, $output_array);

Order date:
preg_match_all('/Order date:\s(.*)/', $input_lines, $output_array);

Total: 
preg_match_all('/Total:\s(.*)/', $input_lines, $output_array);

Pay method: 
preg_match_all('/Payment method:\W+(.*)/m', $input_lines, $output_array);