The Windows license is embedded in BIOS on motherboard.  When you install Windows, license type will be installed accordingly (Home, Pro).  After installation, Windows will be activated automatically when PC is connecting to internet.
I have a 3670, which I think is four years old. The SSD is 100 gb, and I want to upgrade to a 500 or even 1 tb ssd. It has been a long time since I replaced a C drive on a computer. This one came with Windows 10 IIRC.  If I simply take out the old SSD and insert a new one, what then? I do have installation files for Windows 10 on a flash drive. But would Windows in some way, read the serial number or would I have to enter it? Is it on the outside of the shell somewhere, or does that sticker just contain the serial number of the computer itself?
Inspiron 3670 SSD (C) drive upgrade