I have to update some Mac work stations in a business environment from Snow Leopard (10.6) to Lion (10.7). I found that the way is to purchase it from App Store (for 24 EUR). Now the problem is that all my users of the workstations used their own Apple ID to sign in in App Store and thus they have their private credit card information bounded to the account and I can not require them to pay the price of the update. How can I pay for the update with a company credit card?