How many sites is my license valid for ?
When you buy a license, you choose the number of sites you want to install SecuPress on. You can choose 1, 5, 10, or more (unlimited is available as a license upgrade in your account), depending on your need. A single site license can be active for a single site, and so on.
If you run a multisite, just select the number of sites in your multisite. Remember that the plugin affects every single site at once, and it is not possible to not activate SecuPress on an individual site of the network.