If you’re looking for a legitimate copy:

: Specifically tracks and blurs edges for immersive VR/360 content. How To Use RSMB on Premiere Pro! (Full Tutorial)

If you find a website offering a for free, you are likely walking into one of three traps:

ReelSmart Motion Blur (RSMB) is a powerful post-production tool from used to add natural-looking motion blur to digital footage by tracking every pixel from frame to frame. If you have downloaded the demo, you likely see a large watermark over your video; removing it requires a valid ReelSmart Motion Blur activation key . How to Get a ReelSmart Motion Blur Activation Key

: Click "OK" or "Activate." The watermark should disappear immediately.

If you search for a free activation key, you will find: