Even with proper licensing and activation, RcWare DBFB reports a license problem. It may seem that this is because the DB is running on a virtual machine, but the problem is elsewhere - it must be:
<supportedRuntime version = "v4.0" sku = ". NETFramework, Version = v4.5" />
This is because the .NET Framework 4.5 is actually just an extension of FW 4.0 and is not self-identifiable.