How do I enable guest checkout?

You cannot checkout as a guest if you are logged in so guest checkout will not work on sites where "Register To View" is enabled in your main site settings.

You also cannot checkout as a guest if you are selling a "donation" as gift aid requires more information which you need to keep for longer.

Guests cannot login and administer their own accounts (they don't have one). Therefore your administrators will need to facilitate any requests from guests.

Guest checkout data is deleted when the purge data date for the last event they have purchased for has passed and data therefore their data is not stored according to your site wide date retention settings

Guest checkout is not available if the product/ticket is free of charge.

Finally the only difference between guest checkout and registration is that the latter requires a password, so it's worth considering whether you enable it. Guest checkout is not suited when you want to build a community and should really only be considered when selling to the extended community.