When purchased, the first generation Model S 60s (2013 and 2014) had Supercharging access as an option. All other models (except S40) have Supercharger access included.
When purchased has the option of enabling Supercharger support for $2,000. You could also elect to add Supercharger support after the purchase for $2,500.
It’s unclear if this option is still available, so contact service for current availability and pricing.