Ghost Solution Suite does not handle operating system activation, it just deploys the operating system.
If you use Sysprep, this automatically wipes any existing activation and licensing information, so if you are using a Volume License of Windows 7, it will still need activation after deployment.
You have not indicated whether you are using KMS or MAK licensing for Windows 7. If you have a classroom of machines that are being reimaged on a regular basis, I would suggest having a KMS solution would offer the most efficient solution, as the KMS server can then hand out licenses on an as-needed basis.