Properly license Win 10 computer by Wds or sccm

As always forums are not good sources for licensing advice. Licensing is a legal document and you should work with the. Vendor (in this case Microsoft) directly. Or have your lawyer look over any EULAs yoh are concerned about.

There is no free upgrade anymore. Any machine you choose to upgrade needs to have a copy of Win10 purchased for it.  If you plan on using WDS/SCCM, that is "reinagibg" and that right inky comes when purchasing volume licenses.

When purchasing VL, you'll have access to keys to handle the activation side of things.

The answer is not clear regarding using wds deployment

The answer was about as cut and dry and licensing gets. Can't make it any easier. All the more reason to work with MS as a partner.

Thanks
What type of license and how can I activate for 100 computers through WDS

This is the same as your previous question
https://www.experts-exchange.com/questions/29152583/Licensing-of-win-10-option-using-win-7-license.html

1. A license is not activation.  You can be activated without a license, and you can be licensed but not activated.
2. WDS/SCCM have nothing to do with licencing or activation. They simply install the operating system and optionally supply the product key using the unattend.xml (there are hundreds of other options available to be customized in the unattend.xml)
3. To install from WDS/SCCM using a system image requires a VL copy of the software.
4. Enterprise normally activate either via MAK (microsoft activation key) or KMS (key management server) . I use MAK for laptops and other devices that may be away from the domain for an extended period of time and KMS for the rest. MAK doesn't have any limitations where KMS does require 25 requests before it starts issuing keys for a client operating system.

When you use WDS or SCCM, part of the process is creating a task sequence. Part of the task sequence is specifying the OS to be installed. When you import the OS, you can specify a MAK - a multiple activation key - to be used for that OS. It's stored in the task sequence and automatically injected into the OS.

this depends on how you are activating you Windows 7 computers and how you bought your licenses. If you are using WDS or SCCM, I imagine you have Windows 10 Volume licensed. If so, do you have a KMS server already? If you do, then you can just add the Server 2016/Windows 10 KMS key to that server. Here are instructions if you have a 2008 R2 KMS server
https://www.itdroplets.com/add-windows-10-key-to-existing-windows-server-2008-r2-kms/

For 2012, this has good information

https://social.technet.microsoft.com/Forums/en-US/666b8ac6-d39d-43a1-abc5-e7cd9489accc/windows-10-kms-requirements?forum=win10itprogeneral

If you plan to use MAK key, then Michael is correct but if you have access to a MAK key, then you have access to a KMS key and it takes less configuration.
  If you have 2012 R2 AD, you can also setup Active Directory Based Activation. It will be needed going forward anyway.

In both of your questions about this we need to establish how your 100 Windows 7 PCs are currently licenced to best advise you on how to apply licencing to Windows 10.

Do you currently use any form of volume licence for Windows 7?

oops yes multiple activation key vs microsoft activation key.. Face meets palm

The OP has told us so little about his/her environment, it's impossible to give good advice. Which is why I only answered the specific question asked.

Need more info and comments from all experts please