You must be online for the servers to verify the license.
A: No. You must purchase one or use a free upgrade from an older genuine Windows license. activate windows 10 key
A: No. Windows 10 will still receive critical security updates and patches even if it is not activated. However, you cannot personalize the look and feel of the OS. You must be online for the servers to verify the license
Press . A popup should appear confirming your system is activated. Troubleshooting Common Activation Errors activate windows 10 key