No Man's Sky: cross-buy and cross-save
Progress moves across PC, PlayStation, Xbox, Switch and Mac through an account you link on the developer's site.
Does No Man's Sky have cross-buy?
Unconfirmed
The cross-save page does not say whether a separate purchase is needed on each platform.
Does No Man's Sky have cross-save?
Yes
Link a Steam, PlayStation, Xbox or Nintendo account on the developer's cross-save site.
Source
you can share your progress across multiple devices.
Limits of this entry
The page says cross-saving "requires a Steam, PlayStation, Xbox or Nintendo account" for sign-in. It is silent on buying the game again.