Agreeing some users "may possibly have left as a result", Microsoft product marketing services manager Duncan Reid said the company was working hard to make the changes clear.
"The onus was on us to simplify licensing. Partners literally screamed at us to do that and as a result we brought out the new licences," he claimed.
The changes to the licensing, which involve users buying into a regular upgrade path, were announced in May this year and users have until October to conform (see Microscope, 15 May).
"We said from the start that for 20 per cent of our users, the new licensing strategy would prove more expensive, but for the rest it would be more affordable," Reid stressed.
He said it would be more costly for those companies who upgrade less than every four years.
A Computacenter spokesman said its Microsoft team was working hard to allay fears about the new licensing strategy.
Zak Verdi, software services director at Bytes Technology, said businesses needed advice "in order to make the appropriate licensing choice that will most effectively negate the licensing impact".