I can't seem to find a definite answer for this. Early on I did the free upgrade from Win 7 to Win 10, but due to not being able to install and view the old data logs for my "toys" (weather station, radiation measuring equipment etc.) I ended up downgrading until I could find a solution to the problem. I just realized I there are only a couple of days left to get the free upgrade. As I have already done this in the past, do I have a valid "licence key" to upgrade for free in the future?