A Schengen Visa is for 90 days that they allowed out of the Country they live. If they return before their Visa date the Visa automatically expires and it will take another 90 days before they can apply for another to leave the Country again.
I don't know what or why she left. Maybe another business opportunity arose and she never had a choice but to fulfil that obligation or she could have already been in Barcelona Spain a couple of Months prior to coming to the apartment. A number of things could come into play as to why she departed. That no one will likely never know.
She did give one Hell of a Performance while she was there. Imagine if Nora was still there none of this would have ever happened unless she could vilify the spotlight.
Ilona came in on the 18th of November so chances are she'll be there the full term or gone in the next 3 days. Anna came in Dec.19/15. So what her plans are or RLC has in store I haven't the slightest idea.