Duration of validity for Card Nonce

How long is the card nonce valid for after it’s generated via Square Payment form?

Hey @lukel welcome to the forums!

They expire in 24 hours (Web Payments SDK Overview):

Tokenized payment card information. The nonce is a string representing the nonce that was created or null if an error occurred. Nonce values expire after 24 hours .

Thanks @sjosey.

Can I assume that once the nonce is used for a payment, it will not longer be valid?

Yes, that is correct.