Originally Posted by Lux Flyer

When you're booking it should either let you bundle the economy plus in, or when you select seats on the flights show the individual cost for the seats. An economy plus subscription is an option. For ttavel to EZE it needs to be the global option which for only you is $799 for the year, or if you also want a companion would be $999. So if the cost of the seats/bundle is more than that, subscription might be better (or if seats are less but you have more travel in the next 12 months, subscription could also be a good choice).

Also keep in mind you can't choose bulkhead or exit row E+ seats with the pet in cabin.