You can pay with Apple Pay anywhere contactless payments are accepted, with your iPhone or Apple Watch. You will need to authenticate with either Face ID, Touch ID or your device passcode. You can pay in person or you can use Apple Pay to pay when using apps or Safari online.
Paying in-store with Face ID on iPhone - To pay using Face ID with your iPhone - Double-click the side button and glance at your iPhone to authenticate with Face ID. Hold the top of the iPhone near the contactless reader until you see Done and a checkmark on the iPhone.
Paying in-store using Touch ID on iPhone - Rest your finger on Touch ID to authenticate while holding the top of your iPhone near the contactless reader until you see Done and a checkmark on the iPhone.
To pay using Apple Watch - Enter your Apple Watch passcode if requested. Double-click the side button on your Apple Watch and hold the display near the contactless reader. Wait until the watch generates a gentle tap. The screen will also display Done and a checkmark. If your payment is over $200, you may need to enter your card PIN.
More information: https://support.apple.com/en-au/HT201239#stores
Paying when using apps - Look for the buy with Apple Pay icon or choose Apple Pay as your payment method at checkout. Follow the prompts and confirm that your payment, shipping and contact information are all correct. Tap > to change any of the payment information. Use Face ID or Touch ID to confirm your payment with an iPhone or Double Click the side button to confirm payment with an Apple Watch.
Paying when online - For online payments with your Mac with Touch ID, follow the prompts on the Touch Bar and place your finger on Touch ID when prompted to authenticate your payment. For online payments with other Mac models, use Bluetooth to select your iPhone or Apple Watch to authorise payments in Safari. You will need to be signed in to the same Apple ID on all devices.
More information: https://support.apple.com/en-au/HT201239#safari
Don’t share your device passcode with anyone else or let anyone register their face or fingerprint on your device.