You will need to use the Solarwinds License Manager on the old system to deactivate the license. It will send it back to the licensing servers and make a new key in your Customer Portal.
If the old system is no longer available, you will need to Contact Customer Service to reset the license.
Calling in: 24/7 Support at 866.530.8100. Please have your Solarwinds ID available when you call in. Our system will ask for it on Options 1 and 3. Option 1 will cover License Reset and License Consolidation.
Submitting a case online. To securely create a case online you will need to login to your customer portal.
https://customerportal.solarwinds.com/support/submit-a-ticket/
Login with your Solarwinds ID (Starts with SW) Fill out appropriate details and Support will get E-mail you back.