It depends on how do you activated before.
Microsoft describes the Windows 10 free upgrade as a full version, not a trial. Contrary to these statements, Windows 10 free upgrade does have some restrictions.
•If you upgraded from a retail copy of Windows 7, Windows 8 or 8.1, the Windows 10 license carries the retail rights from which it was derived – can be transferred. But under Microsoft’s rules, you are only entitled to a one time transfer.
•If you upgraded from an OEM Windows 7, Windows 8 or 8.1 license, these are licenses that come preinstalled on a new computer from a manufacturer, and then your Windows 10 license maintains the OEM rights – cannot be transferred.
•If you have a full retail copy of Windows 10, you can transfer it as many times as you want.
•If you performed an Easy Upgrade to the Windows 10 Pro Pack from Windows 10 Home, you can transfer it using Digital Licensing. This is possible because the Pro Pack, while an upgrade, is a retail license attached to the Microsoft Account used to purchase it.
"Can i transfer my free upgrade win10 to different laptop?" - No; Your OEM license cannot be transferred to another device. If you are buying a new laptop then it's very likely to come with its own license of Windows 10 – Ramhound – 2017-09-19T07:39:27.213
As for a retail license that was upgraded, you would have to call the Microsoft Activation Center in order to accomplish that, while technically you can transfer the license Microsoft doesn't make it easy because the upgrade license cannot be transferred (but your original license can be but technically you cannot use both). Yes; it's complicated because Microsoft in 30 years has never given away a license to a newer Os because you had a license to a previous version. – Ramhound – 2017-09-19T07:47:20.717
https://superuser.com/questions/1086984/win-10-free-upgrade-license-transferrable – Ramhound – 2017-09-19T07:48:42.037
I did a bit more research and found out that after you clean install win10 you can connect your Microsoft account and if you already uninstall the license from the old pc it can automatically activated it in the new pc. If the new laptop have win10 home pre-installed do i uninstall it first? – Dizz – 2017-09-19T08:46:54.383
A "Clean install" is just an upgrade where you choose not to keep your personal files, there isn't anything specifically special, about a clean install. You can link the installation to your Microsoft Account no matter what option you choose. Yes; Technically you would need to format your existing machine, disconnect the device from your Microsoft account if it's linked to it, because you can not have a single Windows 10 license. – Ramhound – 2017-09-19T08:54:38.223
No when i say clean install, i mean install the laptop fresh from start with nothing on the hdd. So if i do what you say(format,etc), my new laptop will activate when i connect my account? Did i understand it right? – Dizz – 2017-09-19T09:34:23.023
You indicated your research indicated that was the case – Ramhound – 2017-09-19T09:36:58.530
Ok the only way to make sure is to do that i guess, i'll try it when i get my new one. Thanks for the answer. – Dizz – 2017-09-19T09:41:21.693
I will point out again that, its very likely your new machine will simply come with Windows 10, provided you purchase OEM hardware. – Ramhound – 2017-09-19T09:47:01.263
Yes it says it come with win10 home, my current one is pro updated from win 7. I will probably sell my current one so it will be a waste if i not move it first. – Dizz – 2017-09-19T09:54:27.440
You are going to run into issues if it comes with Windows 10 Home. There are numerous questions here at SU of users who struggle getting Windows 10 installed if they are machine came with say Windows 8.1 Core (or Windows 10 Home) since the Windows installation automatically detects the license stored in the ACHPI table. Since you don't have an actual Windows 10 Professional license key the methods that do work in most cases won't be applicable to your case. My suggestion just pay the extra money for Professional from the get go. – Ramhound – 2017-09-19T10:07:12.390
I guess i'll do what you said, there is seller here who sell win10 pro license for cheap (~$10). – Dizz – 2017-09-19T10:15:29.397
I will caution you of using purchasing Windows licenses that have 90% discount. – Ramhound – 2017-09-19T10:25:52.707
Are there any known issue? I bought some win 7 ultimate license with similar price for my office and my current laptop before, but because i upgrade all of them to win10 i haven't encountered any issue. – Dizz – 2017-09-19T10:45:29.493
I have never seen actual legitimate Windows licenses sold at 90% discount (outside perhaps the Home Use Program offered by Microsoft) but in that specific case the price difference is actually paid by the company not the employee who purchases the license. – Ramhound – 2017-09-19T10:46:33.700