Store Commander Multistore license allows you to manage multiple PrestaShop stores whatever PrestaShop versions you are running.
If all your stores exist on PrestaShop 1.5 or above, you can enable the multistore management feature in the PrestaShop back office (please refer to this article). This allows you to manage all your stores in a single Store Commander 's interface.
If on the other hand your stores exist on various versions of PrestaShop < version 1.5.x, you will not be able to benefit from the multistore management on a single interface because the functionality is only available from PrestaShop version 1.5.x. You will then simply need to install SC on each store using the same license key.
A SC Multistore license is required as soon as you manage more than one PrestaShop store. The license key will then be applied on each Store Commander installation on each of your Prestashop store.