How to install/upgrade Window 10 pro?

[Windows Central Question]

1. Device use : Legion Y7000-2019-PG0 Laptop (Lenovo) - Type 81T0
2. Device OS: Window 10 Home
3. Bought a Window 10 Pro DVD
4. Step have been try:
a. I have follow step use shown by this link "https://www.windowscentral.com/how-upgrade-windows-10-pro" except the last steps I choose "Change product key". I have insert the product key and said the product key entered didn't work.
b. Insert DVD using external DVD driver, not successful and wrote the product key entered didn't work.
c. USB flash also does not successful.
d. I have follow step use shown by this link "https://www.windowscentral.com/how-upgrade-windows-10-pro", click "Got to store" and on the website I click " I have a Window 10 Pro product key". I have insert the product key and said the product key entered didn't work.

 

[Ryujingt3]

My first question is where did you buy Windows 10 Pro from?