Hi @sbindra_9387,
You should create a new free license for your preprod environment. Creating that new license will not affect your production activation. Just to verify, your preprod environment is pointing to a different database and different file storage than your production instance, is that correct?
I know you are running an older version of ProGet, but our guide on how to migrate a server should still work for ProGet 5.1. That guide will show you what you need to do to migrate your production instance to a test server.
Hope this helps!
Thanks,
Dan