Can I use one license key on sites with different domain suffixes (TLDs)

No, domains with different suffixes, or top level domains, like location and business types (.com,.org,.net) or country specific domains (.de, .uk,.nl,.es) are in fact different domains and you need to purchase a license key for each one if you plan on installing different instances of JReviews on them and want to have access to the JReviews App Store.

If you are using the domains as aliases for the main site and you are using a single CMS and JReviews installation then you can use a single license key on the main site and always access the JReviews administration from the main site.