This is a great question and unfortunately, especially with young hunters, it occasionally happens that they have either lost their license, washed it or just simply cannot find it. Although the license number is on the tag, Idaho Code 36-1201(c) requires that your "License must be .......on his (your) person at all times when hunting, fishing or trapping and (you must be able to) produce the same for inspection upon request of a conservation officer or any other person authorized to enforce fish and game laws." So, the answer to your question is yes he needs to have both his license and his tag on his person while hunting. You can solve your problem easily a couple of different ways. First you may go to any Regional Office or Vendor and purchase a duplicate license for your son. Another option would be, if your son intends to purchase any other type of validation for his license such as a two pole validation, archery or muzzleloader validation, migratory bird validation or Sharp-tail validation he can make those purchases and a new copy of his combination license will be generated along with the validation. Good Luck on your hunt!