In order to activate McAfee for new users, you must first create an account on the official website through Mcafee.com/activate, then buy or input your product key. Go to "My Account" or "Subscriptions" after registering, then input the 25-character product key that you found on your package or in your email. After entering your key, McAfee will confirm it and ask you to download and install the app on your smartphone. The procedure is the same for current users: sign in to your McAfee account, go to the "My Account" area, and if you're renewing or upgrading your membership, you'll have the option to enter a new product key. Your subscription will be activated once you enter the key, allowing you to keep using McAfee's protection on your device.