Amazon has launched a new rewards and cash-back program for Prime members, the company announced Tuesday, an incentive for users to purchase more items through its e-commerce site. Prime members who add funds to an online gift card are rewarded 2 percent back on any Amazon purchase in the form of points.

The new program, called Amazon Prime Reload, encourages people to sign up for the Prime service. The $99 per year subscription already includes free two-day shipping and access to streaming content. The program has been a lucrative one for Amazon, with Prime customers spending an average of $1,300 annually compared with about $700 for nonmembers, according to Consumer Intelligence Research Partners. While Amazon doesn't disclose the number of Prime subscribers, Fortune reported that there's an estimated 80 million members in the U.S.

Amazon Prime Reload is a strategic move for the company, which already offers a credit card for Prime members that gives 5 percent cash back on and other deals. And those tactics may be paying off: Despite the retail crisis in America, Amazon could become the first company with a $1 trillion market cap, NYU professor Scott Galloway said on Recode's podcast on Monday.