I was aware of the yearly membership (600$/yr in my RIR), and that they are on a per request basis where you have to demonstrate that you will put those IPs to the use and benefit of the general public, so you need to talk about your users basically, and if you are B2B you need to talk about your client's users.

But in my RIR I don't think there's a 2 year minimum.

Regarding IPv6 blocks do those require a 2 year membership as well? They are probably easier to get.