If you need Pro features temporarily or for testing, Synology provides legitimate ways to access them:
Running more virtual CPUs than the physical core count (Pro allows 4x threads, while the free version is more restrictive). Live Migration: synology vmm pro license crack cracked
If you're looking for alternative virtualization solutions: Report: Synology VMM Pro License Crack If you
If you need VMM Pro but are concerned about the cost, consider these official options: synology vmm pro license crack cracked