I have a multiple sites, do I need multiple subscriptions?
That all depends on how many WordPress installs/domains you have.
Do you have 1 domain or subdomain name and 1 WordPress install? You just need a subscription for one site, no matter how many subsites or languages you have!
If you have more than one domain name or multiple WordPress installs, you'll need a subscription for the number of installs or domains you have. Starting from only 2 sites, you get a discount, automatically. See the discount chart here: Can I use the plugin on multiple sites?