MarketPress with Affiliate cookies with some registered, others not.

I think this is best served by the MarketPress team, but it might be by affiliates. Not sure as it has to do with close integration of the two.

So I had an aborted run last saturday of our live event (server crashed 4x, either due to a DoS attack,poorly executed host resources, or over utilization of javascript from a plugin) with about 400-600 simultaneous users.

My question is thus:

Initially, I had customers option to an A/R form, not register in WP as they would be doing "one-off" product purchases, not purchasing a subscription to the site. Now I have changed the opt-in form to also create a WP user based on their email address.

For those cookies to be affected, do I have to force them to login or can they just continue to purchase using the non-forced login I made available last week?