First on my old laptop which was connected to internet I deactivated the genuine copy by doing these steps :
- Open an elevated command prompt,
- In the elevated command prompt enter slmgr.vbs /upk
I then go to my new PC and open an elevated command prompt,
enter Win + R -> slui 4.
Choose country,
Phone the number provided,
Answer Windows is installed only on 1 PC
Follow instructions and it worked!