This is usually due to a typo. Instead of typing the key manually, copy and paste it directly from your email to avoid confusing '0' (zero) with 'O' (letter) or '1' (one) with 'I' (capital i).
is a compact, case-sensitive alphanumeric registration key used to activate the Hexcmp 2 software. The key format follows this pattern: hexcmp 2 register key
Remember: The most powerful hex editor is the one you use ethically and legally. This is usually due to a typo