Linux boxes? Changed IPs?
Windows 2008/2003, No change if IP’s.
Are you sure you're not confusing them actually being licensed with the trial license period (which lasts 2 weeks)?
Are they virtual machines where they have the capability to have dynamic CPU allocation ?
If so then this is the cause of the licensing issue as the getlic command pulls the number of CPU assigned.
You can amend this before going to the licensing portal.
If you install an BL Agent and import this target right away inside BL console. il will be consider "Alive" for the first 2 weeks. Then after the grace period is will become automaticly "Not Licences" if you never ran the autolic(getlic+putlic) againts this target.
So best pratice, when importing a server inside BL console, always run the autolic agaist it. to avoid this situation.