In the near future (or right now if you live in Japan) your bank account will be linked to your mobile, and, assuming that you’re solvent, payment will be made in an instant. Are you sure you can afford that bottle of ‘Herbal Essences’ William?
But what if someone steals your mobile and uses it to buy countless expensive items? Of course they couldn’t: your phone is protected using ‘biometrics’. That’s face and fingerprint recognition.