Thanks Gary, you explained that very well.
But this explanation belongs on the upgrade order form, not somewhere in a forum.
I just bought a lifetime upgrade licence and only in the confirmation email, it said that it was valid only for one device.
I feel mislead here.
If emclient maintains its position, i feel inclined to abandon the lifetime upgrades and request a refund as per European law.
(I sincerely hope it will not come this far as emclient is a fine piece of software)
Edit:
I was contacted by the sales department very quickly and they sorted me out quite friendly and helpfully. Compliments!