The advent of virtualisation technologies will force software vendors to rethink how they charge for their products, according to analyst firm IDC.

Al Gillen, research director for system software at IDC, told delegates at the SCO Forum in Las Vegas: "As this stuff starts to get onto the market and more adopted, customers will realise that the complexity is not in leveraging the virtualisation technology but the licensing."

Virtualisation technologies blur the border between hardware and software. Instead of running applications on a dedicated system, the technology allows IT administrators to dynamically assign computing resources to different tasks.

But current software licences do not allow users to move applications between systems or occasionally run them across multiple systems.

"The current models are going to lose their relevance," said Gillen, suggesting that software will eventually be sold as a metered service.

In the short term IDC expects vendors to keep using the familiar perpetual licences, but to add flexibility to allow a limited use in virtual environments.