You can park your cark inside the Flora Palace for 3 hours over day free of charge till 10 p.m..
You will park in the garages of the Flora Palace, then you will take the escalators to the 1st floor and go straight through the hall of the underground. (do not entrance to the fee area of the metro) and step out by the entrance - the roadsign Vinohradská a Jičínská ulice, there will be the pharmacy´s laber.
The exact address is Jicinska 10, Prague 2, Vinohrady, 5th floor, ring the bell Apartments Flora.