Expandable memory for use with solid state systems and devices

The present disclosure describes technologies and techniques for use by a data storage controller-such as a controller for use with a NAND or other non-volatile memory (NVM)-to provide a user-expandable memory space. In examples described herein, a customer may choose to purchase access to only a portion of the total available memory space of a consumer device, such as a smartphone. Later, the customer may expand the user-accessible memory space. In one example, the customer submits suitable payment via a communication network to a centralized authorization server, which returns an unlock key. Components within the data storage controller of the consumer device then use the key to unlock additional memory space within the device. In this manner, if the initial amount of memory the consumer paid for becomes full, the consumer may conveniently expand the amount of user-accessible memory.