The moment you download a "preactivated" scanner driver, you are handing over the keys to your system to anonymous hackers in exchange for saving ~$50. Given that identity theft costs an average of $1,400 to resolve, the math does not work.
If you just need to scan documents (not film negatives), is completely free and open source. It works with WIA and Twain drivers and is arguably easier to use than VueScan. No watermarks, no cost. vuescan preactivated
However, security researchers have analyzed popular "preactivated" VueScan torrents. Many of them actually inject a digital signature into your scanned JPEGs that can be traced back to the crack. If you try to submit that photo to a professional stock agency, their metadata scanners will flag the file as generated by unlicensed software. The moment you download a "preactivated" scanner driver,