Sangomacrm PHP error during backup

I get this error while backup:

Working with sangomacrm module
Exporting KVStore from Sangomacrm
Exporting Databases from sangomacrm
PHP Fatal error: Allowed memory size of 2147483648 bytes exhausted (tried to allocate 72 bytes) in /var/www/html/admin/modules/backup/BackupBase.php on line 94

Why is this ? How to fix it ?