I had to read it twice, as the first time I interpreted it as it was free to use for the first year, then you had to pay to continue. On a 2nd reading, the intent then was that within the first year of Win10, anyone with Win7/8 can update to Win10 for free, but upgrades outside that window will have to be paid for. There is no fee to continue use.
Right now, I think this will be a no-brainer for my existing Win8 systems. I’m not so sure I want to update my Win7 systems though, but a year is long enough for me to play with Win10 on current Win8 systems and decide if I like it or not to update Win7 systems also.