DreamObjects Trial?

I just got a notice that I am 3 weeks into my trial period and it is about to expire for DreamObjects and billing will commence in a week.

First of all, I don’t remember ever signing up for DreamObjects and am unclear as to how the billing works when the trial is over. When I attempt to downgrade, return to usage billing, instead of whatever will happen when the trial is done, I get an odd message “Are you sure you want to immediately upgrade to the Usage-Based Billing plan?” …

Can someone please clarify what is going on so I can understand my options and make the right choice?