Yes! Your purchase includes lifetime updates, so any future improvements or refinements to the template will be available to you at no extra cost.
Future updates are not automatically pushed to your customized version of the template, which lives in your Notion workspace. This is not a functionality of Notion.
When you purchase the template, you receive access to a change log that keeps track of all updates made as well as suggestions on how to incorporate any changes into your version of the template.