iPhone re-download feature help

[tracid]

There was a week where the app "Japanese" was free. The price is now $19.99. Since I restored my iphone, I checked the app store which presented the "Buy Now" tab. My question is, what will happen if I tap the "buy now" tab? Will I be charged $20?

Any help will be greatly appreciated, thanks.

 

[DPA]

A box should pop up saying "You have already purhased this application, click OK to download it again for free". You won't be charged.

David