Hi there!
Thanks for contacting us.
Your subscription will be a one-time payment. You will not need to renew later to keep using end-products. But if you need updates and support after the expiration then you need to renew the subscription.
If you have subscribed to a Templates and Extensions plan, and installed the quickstart pack of a template, then you will get all the necessary components within it even the SP Page Builder pro too, as you have got it already.
You have a license key, and it is within your JoomShaper dashboard. So you can use the license key in your SP Page Builder pro global configuration.
You may check the FAQ in the pricing plan page also about "What happens after my subscription runs out?":
https://www.joomshaper.com/pricing#v-pills-general
Best Regards