All your Amazon Echo devices are set to allow voice purchases by default. Of course your kids will find ways to order things on Amazon and subscribe to Amazon music, so if you're wondering if they're ordering from your phone, speaker, or who knows where, this is probably the answer. Here's how you turn it off:
"After you register your Echo or Alexa-enabled device, voice purchasing is enabled by default. You can set up a voice code or disable voice purchasing in the Alexa app using the steps below.
-In the Alexa app, select Settings, scroll to the Alexa Account section, and select Voice Purchasing.
-To enable a voice code, use the toggle to turn voice code on. Alexa will ask you to say a 4-digit confirmation code before completing purchases.
-To disable voice purchasing, use the toggle to turn purchase by voice off. It will still be possible to search for products, add items to your cart, and track orders."