I have acquired LR 4 in 2012 und have to update it to LR 5.7 because awr-files (Sony's RAW-files) cannot be imported in the LR 4-version. I have downloaded the test version of LR5 anready, it works fine and awr are imported as dng without a probem. Since my LR4-serial number, however, is not accepted I guess I have to pay for the update. Is that correct and how much does such an update from LR4 to LR5 cost?
Upgrade to Lightroom 6 is 79 US Dollars.
You don't have to upgrade, you can use the free Adobe DNG Converter and convert your RAWs to DNGs, and then import the DNGs into Lightroom 4.