At you can choose whether you would like to make use of your personal account or not. When you make use of an account, your personal information is saved. This can be convenient when you would like to order again. 

However, if you would not like to save your personal information, you are not obliged to create an account. When you check-out as a guest, your personal information is not stored in an account. When you would like to order again in the future, you would have to fill in your personal information again.