All paid plugins that comes with theme(inside theme package) are licensed to unlimited use with theme without any limitations. Activation required only for direct buyers(for those who bought these plugins directly from codecanyon) and works only for them too, so theme purchase code won't work.
Updates is being managed by theme's internal engine. Furthermore, early updates can break theme capability, so we're testing each release and then send update notifications to our buyers. You'll see message in your WP dashboard where update can be installed in one click.
Read more about plugin registration from Slider Revolution's documentation – https://www.themepunch.com/faq/purchase-code-registration-faqs/