Win10 preview version can be turned free of charge without verifying genuine license

Earlier, Microsoft said it would push the Windows 10 final (equivalent to the official version) operating system to Windows Insiders users on July 29 to show that these members have long been involved in Windows 10 testing.
However, recently, some users said that they have installed the Windows 10 preview version, so the future upgrade "old version" will not be required to provide Win7/Win8.1 genuine license?
Gabriel Aul, head of Windows Insiders, replied that in this case, when the official version of Windows 10 is released, it will be upgraded directly. The implication is that the preview version of Windows 10 can be directly upgraded to the official version without verifying the genuine license.
At the moment, we don't know if this benefit applies to all computers with Windows 10 Preview, but inferred from Gabriel Aul's tone, “Free upgrades may only be valid for users with Windows Insiders .