When ground beef has thawed out fully it will last for up to 3 to 5 days in the refrigerator before going bad.
If you want to keep the thawed uncooked ground beef longer than 5 days then you'll need to freeze it and then it can keep as long as 6 months to a year.
Most times though the ground beef will stay fresh for only 2 days and then it will start to go bad even though at 5 days it should be safe to eat but if it smells bad or smells off then throw it away.