1. A method of using a compliant version of software on a first host, the method comprising: using a processor to perform acts comprising: receiving a communication connection from a guest device that stores a first version of a software item; checking whether said first version of said software item complies with a first policy on said first host; determining that said software item is of a more recent version than said first policy allows; copying a second version of said software item from said first host to said guest device; executing, on said first host, said second version of said software item; and using said second version of said software item to perform a tangible action; said first version of said software item being stored on said guest device by a second host that is governed by a second policy, and said first policy calling for a version of said software item that is not compatible with said second policy to be used on said first host; and the method further comprising: connecting said guest device to said second host after said guest device has been in communication with said first host; and restoring said first version of said software item to said guest device.