You'll be using this 6-digit code whenever you pay online. If I'm not mistaken, you may disable the payment code feature by using password free (no password required in designated apps like Alipay,Tmall, Taobao etc)

Beginner's Guide to Alipay App (Updated on Feb 20, 2017)
http://www.smartshanghai.com/articles/smsh...pay-this-is-how