Welcome to Shopify Community. My name is Olivia and I work here.
Thank you so much for sharing your question with our network. I can definitely walk you through renewing your domain to make sure you don't lose it while you are away from your store.
By default, domains that were purchased via Shopify are set to auto-renew at the expiry date. If this is the case for your domain, then we will automatically charge the card on file for your Paused store.
On the other hand, if you previously disabled auto-renew then you will need to reactivate your store to enable renewal by choosing a plan. Once you have done that, you can switch back to the Full Pause option.
I trust this answers your question, but please let me know if anything else comes up.