Allowed memory size of 1610612736 bytes exhausted

export COMPOSER_MEMORY_LIMIT=-1

php -d memory_limit=-1 /usr/local/bin/composer update

1. Firstly i find which php.ini is working because i was using multiple xampp,
  so using : php --ini
2. after that in that file i updated the memory_limit = -1    

;memory_limit=512M 

On Windows 10;

Goto C:\ProgramData\ComposerSetup\bin

Edit: composer.bat and add memory_limit=-1 in the last line as shown below.

@echo OFF
:: in case DelayedExpansion is on and a path contains ! 
setlocal DISABLEDELAYEDEXPANSION
php -d memory_limit=-1 "%~dp0composer.phar" %*