If I already bought djay (v4.2.3) do I have to pay full price to upgrade to day pro?

If I already bought djay (v4.2.3) do I have to pay full price to upgrade to day pro?

Thanks a lot for your loyal support, Tony. Unfortunately, we have no way of distinguishing between existing and new customers in the App Store, which prevents us from giving a discounted price for loyal customers only. However, we decided that the price of $ 49.99 is still incredibly fair for loyal customers, as well, considering the following facts.

djay Pro is not only a usual update. We have rewritten the entire software from scratch, which makes djay Pro a whole new product. It comes with an overall re-design and a lot of new features, such as Spotify integrations, 4-Decks-Mode, Colored HD Waveforms, etc. 
Furthermore, the price of $49.99 is a one time payment. All future updates of djay Pro are included, so that you won’t have to pay again for extensive updates like djay Pro 1.1, that added Video-Mixing-Mode and CDJ Integration.