If VC is in evaluation mode then this VC can manage the hosts which are assigned free license hypervisor edition but once eval of vc is over then you can not use these hosts anymore in the same VC. Remove the hosts from VC and connect individual host through vsphere client,It will always work, there is no restriction but very minimal features would be enabled like (VM power ops,max Physical RAM 32 GB for a host).
Please let me know if you have any other doubts.
Thanks,
Atul