Why is there a watermark on Storyblocks audio? (iOS/Android/ChromeOS)

Storyblocks for LumaFusion is our in-app subscription service that provides media content that is also iOS compatible. As a subscriber to this asset library, you might notice an audible 'watermark' that plays while previewing audio content. 

As part of our licensing deal with Storyblocks, the audible watermark has to be played in preview. However, the watermark is automatically removed once you download the clip into LumaFusion by putting it on the Timeline.