While I am not 100% certain, I believe your assumption is correct. By making the purchase, I believe you are entitled to an additional 1 year subscription (i.e., the activation or key code is new). I've seen nothing to suggest or dictate when you have to use the code to activate the subscription. So holding onto that activation/key code should not be a problem. In my case, every year I purchased my new subscription when I see a good sale and usually several weeks ahead of when my old subscription is set to expire. And a few days before it was set to expire then I would add the new activation/key code. This may not provide the absolute certainty that you are looking for but I do believe the activation/key code will still be good when you want to use it in April or May 2021.