Thanks a lok CyberCitizen, you give me the right way. Here's my code:
::::: start :::::
@echo off
for /F %%i in (computer.txt) do (
psexec \\%%i -u %user% -p %password% cmd /c "\\share\produkey.exe /shtml "\\share\key\%%i.html"
)
::::: end :::::
So this is a batch file, you run it in same directory than psexec and you use a admin account. With this, i got key from all computer in my domain and if a windows 7 computer have a key in bios, it probably a downgrade from windows 10, so i'm 95% sure that i can install windows 10. The way to confirm this is to start windows 10 setup from dvd, just before getting the part to format hard drive, if the setup ask you to choose the version of windows to install "home, pro...", you don't have a windows 10 key in bios. If you don't see this step, you are good.