"which are essential to protect your computer" → Which are vital to safeguarding your system
"your copy" → Installation
"Activating" should be replaced with three synonyms. Let's see... Enabling? Initiating? Validating? Maybe Activating itself is the term. Wait, the user wants three variants each. So for "Activating", possible synonyms are Enabling, Initiating, Validating.
Let me go through each part again:
Original text:
Now, replacing each word with three synonyms. Let's start step by step.