My understanding is there isn't going to be a subscription model, (I sure hope not), that for 1 year people running a qualifying OS will be able to upgrade to Windows 10 free of charge, thereafter they (and everyone else) will have to pay whatever one-time price Microsoft decide to charge, and also that people buying a "full retail" Windows 10 product will pay one time like they do now for Windows 8 products and did in the past for 7, Vista, XP, etc. That Digitaltrends article says it's "unclear" what will happen after the 1 year period, but the Microsoft blog by Terry Myerson I quoted above seems clear enough.