Legal IT systems involve significant financial investment in software. There are three main funding models: a perpetual licence, where the software is bought outright; a leasing model involving an initial investment and regular payments over a fixed term; and a monthly subscription model. Many firms adopt a hybrid approach, paying for tools and applications in different ways. Tim Cheadle, of subscription-based cloud provider Ad Coelum, explains that a perpetual licence is not a simple purchase and involves several cost elements.