I like how the character limit feature encourages users to write concise and atomic notes, but I wonder if the distinction between “notecard” and “cards” is clear enough - or even worth it?
Do you need to keep the separate card count to make the economics of the trial period work? I guess someone could abuse a notecard-only system and create one extremely long card to avoid hitting the card limit. But that wouldn’t be a good use of Supernotes features, and the frustration might be more likely to convert them to a paying customer! 
If that argument doesn’t convince you to ditch the separate count concept, perhaps it might be worth rethinking the naming instead? One idea that comes to mind is saying that “notecards” (or “cards”) are constructed of “note blocks” (or “blocks”). Each “note block” can hold upto 1200 characters, and “notecards” can contain more than one “block”. Then the Profile count could say “3395 / 5000 note blocks”, which would be a clear distinction to “cards”. What do you think?