When using a redeemed code through Volume Purchase, who owns the copy of a B2B app, ultimately?
Here is the relevant excerpt of the iTunes Store Terms and Conditions:

https://www.apple.com/legal/internet-services/itunes/volume/us/terms.html#VOLUME


  CONTENT CODES
  
  [...] YOU UNDERSTAND AND AGREE THAT THE OWNER OF THE
  REDEEMING ITUNES ACCOUNT WILL BECOME (i) FOR AN APP STORE PRODUCT, THE
  LICENSEE OF THAT COPY OF THE PRODUCT; AND (ii) FOR AN IBOOKS STORE
  PRODUCT, THE OWNER OF THAT COPY OF THE PRODUCT, AND SHALL BE ENTITLED
  TO ALL ASSOCIATED RIGHTS. SUCH LICENSES OR PRODUCTS ARE
  NON-TRANSFERABLE.


for short: only managed distribution retains ownership!