leom81 wrote:
during boot setup, but i saw that if i don't touch the iso with winreducer, i haven't got this problem.

You dont have the issue that I posted in another thread, which winter linked to above, but if you put the PID.txt file in your sources folder as described in that post, you wont be asked to enter a serial.
I dont get asked to put in a serial since I did that.

Note: Put it into the sources folder after you save the changes to the wim with WinReducer, but before creating the actual iso.