Received this today:
"avast! pro family pack is a product designed for people with a Windows Home server (this is why you received a license file) + a number of workstations."
I don't think that this is made clear in the online product description.
In my case, I indicated that I would request a refund for the Family Pack (which I've done), and then just buy a license for the one computer that's used for business. I'll use the free version for my other two computers. The person who emailed me agreed that this would be my best option.
I hope that solutions can be worked out for others.
Stumblingaroundinthedark (still/always)