Over seven million customers now use Starbucks’ mobile payment app, according to  CEO Howard Schultz, speaking during the company’s first quarter results call.

Starbucks’ mobile app is used by customers to make purchases in the coffee chain from a pre-paid account.

“Over seven million customers now use one of our mobile payments apps translating into 2.1 million mobile payment transactions each week with hundreds of thousands of additional Starbucks mobile app downloads each week,” said Schultz.

Payment is made by a user opening their Starbucks app and having a barcode scanned by a sales assistant. The user’s prepaid account is then automatically debited. Users can also access their app to top up their account, view their recent transactions and track their reward points.

Additional figures from the first quarter, which covers the holiday season, show more than $1 billion was loaded onto Starbucks cards, the highest amount ever. One in 10 US adults received one of the company’s cards as a gift during the quarter, an indication of its popularity.

Nearly 20 percent of transactions on Starbucks cards now come through mobile payments.

The company last summer unveiled a strategic partnership with mobile payments firm Square. So far the relationship has involved the coffee chain accepting payments from users with Square apps on their smartphones and selling Square’s card reader in Starbucks outlets. Square is also processing payments for the retailer. Interestingly, Starbucks has also bought a stake in the smaller company.