Shopify can store password-protected customer information including identity, order history, and current order status. Customers with accounts will have the pre-filled, making the checkout process faster.
To use customer accounts you need to have the Online Store sales channel.
How to Enable Customer Accounts
STEP 1
From Shopify admin, click on Settings
STEP 2
Click on Checkout.
STEP 3
Accounts are disabled - Customers will only be able to check out as guests.
Accounts are optional - Customers will be able to check out with a customer account or as a guest.
Accounts are required - Customers will only be able to check out if they have a customer account.
STEP 4
Click Save to apply the changes.