Can you take a screen shot of this advert? Is this for a web/HTML form or a PDF? There shouldn't be any pop-up advertisements that I am aware of. You could also send me a link to your form, or PDF to email@example.com and I will take a look.
Another thought a co-worker brougt up is that maybe this is a form that was shared with you by a "Free" level user, if that was the case the features and messaging related to that form would be at the Free level (at the authors subscription level).