Allowed memory size of xxxx bytes exhausted

[maulikpatelbtech]

[root@ip-xxxxx html]# nginx -v
nginx version: nginx/1.12.2

[root@ip-xxxxx html]# php --version
PHP 7.1.15 (cli) (built: Mar  1 2018 13:09:01) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.1.0, Copyright (c) 1998-2018 Zend Technologies
    with Zend OPcache v7.1.15, Copyright (c) 1999-2018, by Zend Technologies

I am using aws Linux ec2 with m5.large instance. I got the error "Allowed memory size of xxxx bytes exhausted ... ".
I already tried to ini_set('memory_limit','2048M'); even if i increase the limit it always gives me an error.

$s3 = Yii::$app->get('s3');
$s3->commands()->upload($upload_photo, $full)->withAcl('private')->execute();