There are two things here.
1) The "Free Version" vSphere Hypervisor is not time limited.
2) The "Free Trial" is giving you access to the features of the full product for a limited time *on top of the free version*.
If you want those features back, you should pay. Or you can get the 60 day trial back by completely wiping the machine and doing a re-install from there.
The fact the VMs are still there implies you didn't do a full wipe.