From the link, there is a store and "optional subscription" to get store-bucks so I'm guessing there are cosmetic items and/or convenience items.
If I'm reading the article correctly, you might also need to pay for new story content -- they mention existing owners getting the next bit of content free, but I didn't see "all content forever free"
So you buy the core game now, then probably buy expansion packs later.
In contrast, Star Trek is really "completely free to play" - download, pay zero, play all seasons / episodes. For solo and co-op you'd ever need to spend a dime unless you want a specific uniform (like mirror universe Empire) or for some slightly better ships that are not needed for any of the content.