If you have a monthly subscription, unused credits will roll over and accumulate in your account up to 2x the credit limit according to your plan.
I'm not able to see your account right now since the URL wasn't shared but let's say you have 10k credits, it means that you'll be able to have up to 20k credits.
If you buy an annual plan, you get all your credits upfront, and you can use them however and whenever you’d like.
You can read more about the Credit Roll Over Update here. Let me know if you have additional questions!