Retainers, confirmed, you have to pay for them.

[Starlord]

They are going to make it so you want to pay for them. A majority of players will feel like they need it. That's how F2P games work with their cash shops. They create this "I need this in order to not feel like I'm missing a benefit of the game" This is pretty much a bump in monthly sub price for most and the ones that don't do it will feel like they aren't getting the full benefits of the game.

It's something no one really needs. If they get it, that's thier choice, but you really don't need a 3rd hell, I got by with just 1 retainer for 4 months before activating my second. (currently sitting at 166 free spaces in total).