An account in Quantum it's the equivalent to a subscription. Once a subscription has been purchased, a Quantum account it's created in Socialmetrix systems. The account it is owned by the person who paid for it, and this role it is not transferible.
Once the account it is created, projects can be created inside of it, and each project can have several members assigned to it. Accounts are, effectively, containers for projects.
Accounts allow you to group projects. For example, you might create, or be a member of, a project for your clients social profiles, and have a separate one for a personal work.
Members of each project could be the same or different, depending on the needs of the account Owner and/or Manager who are the "roles" who can create projects and invite members.
Members of an account can´t be in two different accounts (subscriptions) using the same email and Facebook credentials to login. Quantum it is not a multi account app for the moment. Two different email addresses and two different Facebook credential will be necesary in case you need to login in two different accounts.