The answer to such a question is not possible because everything depends on whether the license has been transferred in the right way, in accordance with point 4a of the license agreement:
4. Transfer. The provisions of this section do not apply if the software is purchased by the consumer in Germany or any other country listed on the site (aka.ms/transfer); then the transfer of the software to a third party and the rights to use the software must be in accordance with applicable law.
a. Software pre-installed on a device. If you acquired software pre-installed on a device (or if you upgraded from software pre-installed on a device), you may transfer the license to use that software directly to another user provided you also transfer the licensed devices. This must include the transfer of the software, if provided with the device, as well as the original Windows label with the product key. Prior to receiving the software, said user must agree that the terms of this agreement apply to the assignment and use of the software to another user.
If the computer has only a certificate and there is no software installed on the disk, formally there has been no legally effective transfer of rights resulting from the license granted to the original user. The original user did not transfer all the components of the license – specifically, he did not transfer the software.
It is therefore illegal to install the software on such a computer. It doesn’t matter that the product key is stored in the BIOS or is on the sticker (COA) and the activation was successful.
The fact of successful activation is often treated as an indicator of the genuine software, while the license agreement explicitly states:
point. 5 (…) Successful activation does not confirm that the software is genuine or properly licensed. (…)
The correct transfer of rights under the license covers all its components:
– hardware on which the software is installed
– software installed on the hard disk (in the version received by the original user)
– certificate of authenticity with a key or the product key stored in the BIOS and the GML (Genuine Microsoft Label).
The use of recovery media provided by the hardware manufacturer in no case can be used to “legalize” a given copy of the system.
Recovery media are only used to recover the software after a failure or replacement of the hard disk, and not for installation on a clean disk by the next owner.
The recovery media downloaded from the manufacturer’s website cannot be treated as a software component to which the license applies and in this way “supplement” the set of components required by the license provisions.
An identical perspective describing the license transfer procedure can be found in the accompanying official Microsoft information (attached so as not to be accused of over-interpretation).
The reality is that practically all computers, coming to our country have their hard drives erased and, in order to be properly licensed, it is necessary to install a new license. Unfortunately, practice shows that license provisions regarding the correct transfer of license rights are omitted, and, for many users, the fact of successful activation and possession of a sticker (COA) is sufficient and does not arouse suspicion.
You can download the Windows 10 license agreement and the Microsoft information leaflet explaining when a new license is needed for used equipment.