If you are looking to upgrade from the free version, uTorrent offers three paid annual subscription tiers through their official download page :

Q: How do I activate my Utorrent Web License Key? A: To activate your key, open Utorrent, go to Preferences, select Web License, enter your key, and click Activate.

If you see websites offering:

uTorrent Web is a popular torrent client that allows users to download and manage torrents directly from their web browser. While the software is free to use, some features are restricted to premium users, which can be unlocked with a uTorrent Web License Key. In this article, we'll explore the benefits of using a license key and how to obtain one.

Don't risk your digital safety and personal data for a non-existent key. The software you want is already free—you just need the right download link.