If you have an account please login of Create a new account.
Click on Redeem your Retail Card for activation.
Enter the activation code you have received on your email and your account email address, then click Next.
This step is for language options and will not always show up. If it shows up you can choose any country with EN extension, it will setup English version.
You will be asked to sigh up for auto renewal, you do not need to auto renewal, you can click on No Thanks.
You are done with the first key, click on the My Account and go to Step 3 to activate the second key. Enter the second key and your email address again just like Step 4.
Once you enter the second key you will be asked to add the subscription on top of your current one, if you have multiple subscriptions and would like to choose to add on the another subscription you can choose it on this page.
You have added another year to your subscription.
If you have more than 2 keys please repeat this process to activate all of your keys, each time you will add another year to your subscription.