Until the vacuum sealed package is opened, we advice to keep it in the fridge as it will be preserved longer at constant temperature; but if you plan to consume it shortly, you could keep it outside the fridge without problem.
Once the package is opened and partially consumed, we advise you to keep it in the fridge, inside a tupperware or any other recipient with no direct contact with the air, as it won't be overdried. You can also keep it in the sachet in which you received it, properly closed to avoid over-drying it.
Ham should be consumed at room temperature, when it will have a lustrous appearance. When too cold, the fat will appear opaque.