In the summary of features of Store at: https://exp-resso.com/store it states you can "Optionally automatically register members during checkout"
But I can't find the setting in the control panel or any documentation on how to set this up...
Can anyone point me in the right direction please?
-- EDIT -- Figured this one out -> This is possible via the register_member parameter of the checkout form or by using a register member field in the form. Adrians answer below has full details.
Thanks for your help!