1) We monitor your transaction and compare them to local thresholds so you know where/when you may need to register: https://stripe.com/docs/tax/set-up#monitoring-your-obligatio...
2) We provide documentation/links to the exact sites to register: https://stripe.com/docs/tax/registering#list-of-state-and-co...
In the future though we'd love to also offer registrations on your behalf, this is just the beginning!