Article continues below advertisementIf you've ever split a dinner, booked a last-minute trip, or Venmoed a friend for concert tickets you definitely couldn't afford, you already know the app has quietly become a running record of your social life. Now, Venmo is betting those everyday moments can do more than just keep things even, they can actually pay you back.The platform is expanding Venmo Stash, its rewards program, giving users up to 5% cash back when they spend using the Venmo Debit Card or check out with Venmo at select brands, restaurants, and retailers.