That seems to be the case, unless they are being particularly nasty.
Also this
http://www.anandtech.com/show/9334/m...fter-upgrading
says that once you've got the W10 update, your existing Win 8.1 licence key will activate a fresh W10 install without issue. However it's not clear whether if you move your install to a different machine whether you'd have to do a two-step install i.e. Win 8.1 > 10.