National Australia Bank's new mobile wallet product, NAB Pay, was downloaded 18,000 times in its first month and customers have used the service to make 60,000 transactions.NAB Pay, which was launched in January, allows customers to use their mobile phones for payments without the need for a payment card.Customers need a compatible Android device, the latest NAB mobile banking app and a NAB Visa debit account or Visa Qantas or Velocity Rewards credit account.The credit card accounts were added to the service last week.NAB executive general manager for consumer lending, Angus Gilfillan, said in a statement that the number of customers using NAB Pay had significantly exceeded expectations.The average spend using NAB Pay is A$13, compared a $19 average spend when customers use a contactless card. Compared with contactless card payments, a relatively high proportion of NAB Pay payments are in cafes, restaurants, fast food stores and supermarkets.