To "protect" a VM running on free ESXi you do NOT make the system more fragile by adding snapshots !!!
Instead you remove all snapshots - make sure the vmdks are eager-zeroed provisioned and then write down the mapping of the existing fragments.
Store the textfile with the mapping outside of the ESXi.
How to create a textfile with the mapping::
vmkfstools -p 0 name-flat.vmdk > name-flat-mapping.txt
Then copy name-flat-mapping.txt to your admin-host.
This procedure "protects" your vmdk against accidental deletes and VMFS-corruption.
And by the way ... creating cron-jobs in free ESXi is not trivial !
Ulli