Hi Sish,
This is Tamal trying to answer your question!
Let me try one by one.
- Windows Home S/L is not free. You paid for it with the hardware itself & the version is called OEM. May be Manufacturer purchase it in high volume & in discounted rate, so the end user does not feel the price.
Person who purchases only the hardware (assemble their own computer with different components from same/different manufacturer) not the OS (windows) bundled, they need to purchase & activate windows separately. May be Home/Pro etc - If it's asking to upgrade to pro version that means it's offering you more functionality like domain Join, Group policy, BitLocker etc https://www.microsoft.com/en-us/windows/compare... may check this for details.
- Which version to install in a PC is hard coded in BIOS until the settings are changed so installer knows automatically which version to install Home/Pro.
- Since windows 10 activation status is saved against hardware ID on Microsoft database, so it activates automatically on a machine that was previously ran windows in activated condition, as soon you connect the PC during or after windows installation. You can reinstall with or without a key, but the PC will activate. It is true for windows 10 & 11 and an OLD compatible PC capable of running windows 11 was upgraded to windows 11.
With new hardware there is no record of the hardware in MS Database, so it asks for a key.
- Windows/Microsoft may offer future builds to be free upgradable on the same hardware as past (windows 98>2000>XP>Vista>Windows 7>Windows 8>Windows 10) My Old PC Ran from Windows 98 to Windows 10 but now obsolete with windows 11 and I have purchased a new Laptop compatible with windows 11. Maybe you can upgrade to future versions If your current hardware is fast & compatible enough by then specification. But there is no guarantee or warrantee. Totally depends on company policy and hardware capabilities.
- You are using windows totally legally so please don't worry about that.