The acceptance criteria you have listed are really a mixture of stories and tasks.
Given your example story:
As a user I want to register and log in so that I can register on the application and start using cloud memory
I would break that down in to:
As a user I want to register so that I can gain access to and start using cloud memory
As a user I want to log in so that I can securely access my cloud memory account
Several of your acceptance criteria are also user stories. For example:
As a user I want to be able to change my password so that my account is more secure
As a user I want to be able to register using Facebook so that I can quickly and conveniently register without typing in all my details again
...and so on.
Acceptance criteria are story specific requirements that must be met for the story to be completed. They are a technique for adding functional detail to user stories. Acceptance criteria are often added during backlog refinement or during the sprint planning meeting.
Some examples of acceptance criteria:
No password longer than 16 characters should be allowed
VAT should be included in all figures
These acceptance criteria add details to the user story and they also provide a convenient guide for testing the completeness of the story.
As a part of a user story, you might define some sub-tasks which are related to implementation. For example, as a part of the registration user story the development team might add a sub-task:
Add a "Register" button that the users can click on
Add in an HTTP redirect for unregistered users to the registration page
Tasks are used by the technical team to help them organize the work on the story. Typically tasks would be of no interest to non-technical people.
Definition of done
The definition of done is a list of things that need to be completed for any story to be considered done.
The definition of done is agreed by the team prior to starting work. It covers what the team feels is necessary to consider any story done.
Examples might be:
Regression testing completed
User documentation updated to reflect new story
Seen by and approved by the Product Owner
Performance testing benchmark achieved