"See answer #1" - to log in there I need a customer number, and have no idea now what that might be. Long ago I found I had two different customer numbers, and have the impression each payment event generates a new customer number.
In any case I find I now have 3 accounts, all valid: one that expires 6/1/2015 for one device, one that expires 7/30/2015 for three devices, and one that expires 11/12/2016, the two year license I just purchased, for one device. Not being able to log in to create a ticket, I tried phone support, but found that because of time shift they are closed. Try again tomorrow, perhaps. They close at 8 pm Eastern time - and I get off work after 5 pm Pacific time. Not allowed to make personal phone calls during working hours. Maybe at lunchtime.
When I paid for this last subscription, a week ago tomorrow, I learned afterward that my existing subscription on this device (my laptop) had 201 days to run. 201 days from November 12th is June 1 2015. That would mean that the other two subscriptions are not currently attached to any device (the one for the XP machine expired some time ago and was not renewed although I paid for a renewal (the 3 devices license, I think). At present I have one device attached to the Internet (the Win 8 laptop on which I am typing this) and one not attached to the Internet (the XP desktop). In due course (probably a few months from now) I will have a new desktop and will want to add that as a second device. I also have (currently, after my latest subscription) Avast mobile on my Samsung Galaxy S5. Don't know which account that is attached to.
I am still mystified as to why, with 201 days left on the current subscription, Avast notified me that my subscription had expired and that I was not protected. Being well aware of the nasty stuff currently floating around the Internet, I panicked and immediately renewed the "expired" subscription - which in fact, as I found out immediately afterward, still had 201 days to run.
I'm hoping the phone support folks can sort this out.
Anyway, thanks for listening.