: On a small slip of paper or card included inside the original big box. Common Formats
For digital purchases, you can find your CD key: half life cd key 25 digits
In 25-digit keys, the letter is almost never used to avoid confusion with the number 0 (Zero). Similarly, the letter I is rarely used to avoid confusion with the number 1 . If your key is failing, try swapping zeros for the letter O. : On a small slip of paper or
: On a sticker located on the back of the CD case. half life cd key 25 digits