In some mobile storage devices, content protection is afforded by dividing the memory into separate areas where access to protected areas requires prior authentication. While such feature does provide some protection, it does not protect against a user who obtained a password by illicit means. Thus, another aspect of the invention is based on the recognition that a mechanism or structure may be provided to divide a memory into partitions and so that at least some data in the partitions can be encrypted with a key, so that in addition to authentication that is required for accessing some of the partitions, access to one or more keys may be required to decrypt the encrypted data in such partitions.; In some applications, it may be more convenient to the user to be able to log in the memory system using one application, and then be able to use different applications to access protected content without having to log in again. In such event, all of the content that the user wishes to access in this manner may be associated with a first account, so that all such content can be accessed via different applications (e.g. music player, email, cellular communication etc.) without having to log in multiple times. Then a different set of authentication information may then be used for logging in to access protected content that is in an account different from the first account, even where the different accounts are for the same user or entity.