BACKGROUND [0001] This Background is intended to provide the basic context of this patent application and is not intended to describe a specific problem to be solved. [0002] Pay-as-you-go or pay-per-use and subscription business models have been used in many areas of commerce, from cellular telephones to commercial launderettes, hi developing a pay-as-you go business, a provider, for example, a cellular telephone provider, offers the use of hardware (a cellular telephone) at a lower-than-market cost in exchange for a commitment to remain a subscriber to their network. In this specific example, the customer receives a cellular phone for little or no money in exchange for signing a contract to become a subscriber for a given period of time. Over the course of the contract, the service provider recovers the cost of the hardware by charging the consumer for using the cellular phone. [0003] The pay-as-you-go business model is predicated on the concept that the hardware provided has little or no value, or use, if disconnected from the service provider. To illustrate, should the subscriber mentioned above cease to pay his or her bill, the service provider deactivates their account, amd while the cellular telephone may power up, calls cannot be made because the service provider will not allow them. The deactivated phone has no "salvage" value, because the phone will not work elsewhere and the component parts are not easily salvaged nor do they have a significant street value. When the accoimt is brought current, the service provider will reconnect the device to network and allow the subscriber to make calls. [0004] This model works well when the service provider, or other entity taking the financial risk of providing subsidized hardware, has tight control on the use of the hardware and when the device has little salvag(; value. This business model does not work well when the hardware has substantial uses outside the service provider's span of control. Thus, a typical personal computer does not meet these criteria since a personal computer may have substantial uses beyond an original intent and the components of a personal computer, e.g. a display or disk drive, may have a significant salvage value. [0005] In a typical pay-as-you-go computing system, a user purchases a code that is redeemable for a number of computing hours at a specially-equipped electronic device. The user may add time to an existing acaiimt balance by purchasing additional codes. However, to ensure security of the user's time balance and securely track consumed time, the system stores data representing the time balance in a secure module at the device itself Storing the user's time balance on one device presvents the user from accessing computer services at any machine other than the device containing the account balance. SUMMARY [0006] This Summary is providedl to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. [0007] A form of removable storage, such as a xmiversal serial bus (USB) flash device (UFD), may allow secure storage of and access to a time balance of a pay-per-use or subscription computing system. A computing device may establish a secure connection to a portable secure computing device to access a stored time balance or other device-enabling, exhaustible data. Dviring operation, the device may deplete the balance. Upon reaching a threshold depletion of the balance, the user may add more data to continue device use. The device may include a processor and storage including identification and subscription data. Further, the device may store configuration data that may be used by the computer to bind the device to a particular subscription service or internet service provider. BRIEF DESCRIPTION OF THE FIGURES [0008] Fig. 1 is an illustration of a computer that implements a method or includes an apparatus for using USB flash devices and other portable storage as a means to access prepaid computing; [0009] Fig. 2 is a simplified and representative block diagram of a storage device to enable prepaid computing; [0010] Fig. 3 is a simplified and exemplary block diagram of a system supporting a pay-per-use and subscription business model; [0011] Fig. 4 is a simplified and exemplary block diagram of a method for enabling a secure computer using a portable storage device to monitor and store an amount of purchased access or subscription time in a prepaid computing system; [0012] Fig. 5 is another simplified and exemplary block diagram of a method for enabling a secure computer using a portable storage device to monitor and store an amoimt of purchased access or subscription time in a prepaid computing system; and [0013] Fig. 6 is a yet another simplified and exemplary block diagram of a method for enabling a secure computer using a portable storage device to monitor and store an amount of purchased access or subscription time in a prepaid computing system. SPECIFICATION [0014] Although the following text: sets forth a detailed description of numerous different embodiments, it should be understood that the legal scope of the description is defined by the words of the claims set forth at the end of this disclosure. The detailed description is to be construed as exemplary only and does not describe every possible embodiment since describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims. [0015] It should also be understoo