If you install ESXi without entering a license key you can test full Enterprise Plus features for 60 days. After these 60 days a license is required to power on VMs.
There is a free Hypervisor license and there are paid Essentials/Essentials Plus/Standard/Enterprise Plus licenses.
PowerCLI scripting does not work with the free Hypervisor license.
PowerCLI can manage snapshots and you can run PowerCLI scripts via scheduler.
Set-VM cmdlet can revert a VM to a snapshot.
For example you could create a Windows or Linux VM with PowerShell Core + PowerCLI installed, write a script which reverts VMs to snapshot and run that script via OS scheduler.