Flickr photo/laffy4k

Historically, people have paid for software by buying a one-time license. But a Microsoft patent filing could flip that model on its head, essentially creating a way to issue "time-based" software licenses.

That raises the possibility of Microsoft charging by the hour, day or month. That's already a component of many software-as-as-service business models. But the Microsoft patent -- dubbed "Time-Based Licenses" -- provides more detail on where things may be headed when it comes to the future of software purchasing.

The filing acknowledges that some systems already allow software to be licensed for a predetermined period of time, but those offerings are "not flexible enough to issue licenses suitable for a number of different licensing business models."

Here's the nitty gritty on how it would work (Also see image) :

The licensing platform may send a request for a time-based license to the activation server via a network. The request may include a product key associated with a software product. The activation server may determine a type of time-based license to issue based on information stored in the licensing database with respect to the product key included in the request. An activation response, including the time-based license, may be sent to the licensing platform, which may use the time-based license and may grant a right to use the software product for a predetermined period of time, as indicated by the time-based license.

The patent -- located here -- also indicates that time-based licenses could usher in a new type of business model:

The licensing business models may include, for example, a non-renewable evaluation of a software product, a renewable trial of the software product, a one-time promotion of the software product, a subscription for use of the software product, or other licensing business models for use of the software product.

[Hat tip to "theodp' who wonders if paying by the hour will be the business model for Windows 8]

[Flickr photo via laffy4k]