So based on your information that you have a license number but lost the actual product key for Windows Server 2019, so I will give you some recommend steps to retrieve or request it:
Step 1: Identify Your License Type
First, confirm what kind of license you have. The steps to recover the key depend on this:
- Retail License (purchased from a store or Microsoft Store)
- Volume Licensing (from Microsoft’s Volume Licensing Service Center - VLSC)
- OEM License (pre-installed on a server from Dell, HP, Lenovo, etc.)
Step 2: Recovery Based on License Type
- Volume Licensing (VLSC)
- Visit: https://www.microsoft.com/Licensing/servicecenter
- Sign in with the email/account used to purchase the license.
- Navigate to "Downloads and Keys".
- Find Windows Server 2019 and retrieve the key there.
-> If you don’t have access to the account: Contact Microsoft Volume Licensing Support: https://www.microsoft.com/en-us/licensing/existing-customer
- Retail License
- If you purchased it through the Microsoft Store, go to: https://account.microsoft.com → Sign in → Order history → Check license info.
- If purchased via a third party, check:
- Your email confirmation
- Printed card or box with the key
But if you lost it:
- Contact Microsoft Support: https://support.microsoft.com/contactus
- Provide proof of purchase or your license number.
- OEM License (Pre-installed)
- The key might be embedded in the BIOS/UEFI of the server.
- Use the following PowerShell command to check:
(Get-WmiObject -query 'select * from SoftwareLicensingService').OA3xOriginalProductKey
- If that doesn’t work, check the sticker on the server or the packaging.