No, installing a new System HDD won't cause you to lose your Windows license.
No, installing a new System HDD won't cause you to lose your Windows license.
The license is linked to the motherboard, but since you're using the original motherboard, you should be fine. Once transferred, you won't need to re-enter the license key—just log in to your MS account.
Your PC probably has a COA sticker with the activation code somewhere on the case. If it was preinstalled with 8/8.1 or 10, the BIOS should already have the Windows key built in. You can reinstall Windows easily using either approach—ask for the key if needed, or let it detect it automatically.
Thanks for the clarification. To put it simply, the software was already installed with Windows 7, but I upgraded to Windows 10 last year. It seems it recognized the license without me entering it again. I upgraded using the same hard drive as before, so I’ll make sure to keep the license number safe this time.
Windows 7 COA keys still work for Windows 10, or at least for Windows 7 Pro. It could be helpful to try a key finder tool and save the Windows 10 CD Key from Magical Jellybean. Removing your old HDD won’t force Windows 10 to stop working if you later install it on a new drive. If reactivation isn’t possible, you can clone the old HDD onto the new one using software like Macrium Reflect.
I was taken aback when the PC started Windows 10 on its own, expecting the watermark until I could obtain a license. It seems they view this as a free upgrade. I used Windows 7 Home Premium before. I recall using the JellyBean program then. I might need it to retrieve the key since the original case is missing. Are Ashampoo Backup Pro and Macrium Reflect the same product? I’m curious because I already own the latter, which came with other tools. Otherwise, I could download Macrium.
Ashampoo appears to be an imaging tool. Since I haven't used Ashampoo before, my opinion is limited. Generally: Cloning programs create a precise duplicate of your computer's partitions, while imaging software tends to copy essential system files, drivers, and apps.