If you are a developer testing software, you might utilize the Windows Insider Program. Microsoft sometimes allows installation of Insider Preview builds without activation for testing purposes, but this is not intended for daily personal use.

| Source | Validity for Parallels | Notes | |--------|------------------------|-------| | Retail key (Microsoft Store, Amazon, Best Buy) | ✅ Fully compatible | Tied to your Microsoft account. Can be transferred to other PCs later if you deactivate. | | OEM System Builder key | ✅ Compatible | One-time use, tied to the virtual machine. Cheaper than retail, but not transferable. | | Volume License (business/education) | ✅ Compatible | Requires an organization’s activation server. | | Key from an old PC’s sticker (Windows 7/8/10) | ⚠️ Sometimes works | You can try during installation. Windows 11 may accept valid Windows 10 keys, but older ones (7/8) are hit-or-miss. | | “Cheap” keys from third-party resellers | ❌ Risky | Many are stolen, volume license abusers, or MSDN keys. Microsoft can deactivate them at any time. |

Because Parallels emulates a standard PC (TPM 2.0, UEFI boot, virtualized hardware), it accepts the as a physical Dell, HP, or custom-built PC.