He's referring to the monthly recurring supportership for PC I believe, 1 dollar a month for Tier 4.
You have to sign up for that manually so if you just donate a bit now you won't be signed up for it. Although if you plan on donating anyway at some point you might be better off, because you'll have tier 4 perks while not having paid the 20 dollars for them until 20 months goes by, and then you can cancel the subscription and keep tier 4.