Good morning, @123493.
Welcome to the Community!
A validation code for QuickBooks Desktop is a unique number used to activate and register the software. It's a required part of the installation process and can be obtained by contacting Intuit support, logging into your Intuit account or CAMPS, or by checking the original physical packing or email if you purchased online.
If you can't find it in the last two options I gave above, I recommend contacting our Customer Support Team.
Feel free to reach back out if you have any other questions or concerns. Take care!