Hey Jason,
Sorry for the confusion here! You can use the plugin on a multisite network without a multisite license. However, using a non-multisite license will display a nag in the admin to upgrade and the plugin will not allow you to network activate it across the entire network.
If you are using the plugin on a single site within the network, then you can certainly install and activate it on that one site rather than the network as a whole. There’s certainly no need to pay the upgrade for that.
Does this help clarify things a bit? We have a post that elaborates on this much more, but please let me know if you have any follow-up questions about the licensing and I’d be happy to help as best I can.
Thanks,
Geoff