The free sandbox does not include data persistence, so if that's something you would like, then signing up for the free trial of Premium would be the next step. And if you want an extended trial beyond the default 7 days, just let me know; always happy to set that up.
1. Is this auto-saved? When I'm about to close it, Chrome warns me about losing data.
2. I think it does auto-save, but when I return, I'm blocked by a pop up with 2 buttons: Upgrade or Remove Data. OK... how do I resume?