I think it's from the date of the first installation/activation but I could be wrong. Subscription questions are best answered by Customer Service whom you can phone free of charge:
To speak with a Customer Service representative, call 1- 866-622-3911. You may be asked for your registered email address and order number. Telephone charges may apply.
Average contact length: 10 minutes
Estimated wait time: 5-10 minutes
Hours of Operation: Available daily, 6am-6pm Pacific
I just spoke with McAfee Customer Service and they confirmed that it is from the date of initial install/activation
I thought so. All the best.