loop.php

$products = array();

foreach($arr['accounts'] as $val) {
	
	       $account_id = $val['account_id'];
	       
	       	      $ch = curl_init();
	
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); 
	curl_setopt($ch, CURLOPT_URL, 'https://api.appannie.com/v1.2/accounts/'.$account_id.'/sales?break_down=product&start_date=2015-01-01&end_date=2015-01-31');
	curl_setopt($ch, CURLOPT_HTTPHEADER, array(
           'Content-Type: application/json',  
	   'Authorization: Bearer 8a2d2958e05107d04ac4bb25687dfb2b56366de7'
        ));       
	
	$products[] = curl_exec($ch);
	curl_close($ch);     
}
print_r($products);