I can't find any information on the purchase page - are any of the license options multiple domain licenses?

No, they are all single site licensees.
You can read the terms HERE

Basically, you can run one instance of the UBB per license; have multiple sites? You'll need multiple licenses.

OK, thanks.

If you had a LOT of sites I'm sure they might consider a discount. But probably not just for a couple sites.

I asked about a discount for multi licenses some years ago, I believe I was told 6 licenses or more would constitute a discount; but that's something you'd have to ask at a sales helpdesk ticket.

I'm going to probably buy and setup a few sites but not sure I'll be doing a forum for them at this time, but if I do I certainly will buy UBB. I just like how it works better than many others and I'm an admin on a couple others.

See, what i was planning to do for some sites is have one dedicated to a forum, then have sections on that forum for the other site...

How many site do you need to get the discount on the license. I have three sites perhap four in the next couple of months. Will the discount apply then

If you buy, 3-5 licenses, it drops to $134 per license. 6-10, drops to $129.

And you don't need to purchase them all at once. When you order an additional license from your members area page it will determine how many licenses you have currently, that have current members area access, and then apply the discount.

So, say you buy 2 licenses now. It's going to be the standard price. If you buy a 3rd in a month, you'll only pay $134 for it.

but if you bought all 3 now, they would be $134 each ?

Yes, if you buy 3 now it's $134. Basically multi-license discounts break down as:

1-2: $139
3-5: $134
6-10: $129
11-15: $119
16-20: $109
21-25: $99
26+: $89