To fill out the information from my post that Sad Crab linked to, there are B versions that are not the Public version that you can access if you have paid once here on Itch which will have more content than the 0.11A version.
Before the current Public version, 0.10.7, the Public version was something like 0.9.12. Since you have paid here on Itch once, you had access to all Beta versions, which then was 0.10B up to 0.10.6B. You can and will continue to be able to download those versions.
So to clarify, you pay ONCE for access to whatever is the current A version (which then was 0.10A) which is a one time access to that Alpha version. But it has granted your Itch account access to all BETA(B) versions. Previous, current and future.
So if you want the 0.11A version you could pay here on Itch again, but it would be a bit of a waste of your money, as you will still get all the B version they release until the next Public version as you have already paid once. If you really want to get your hands on 0.11A I'd recommend becoming a Sad Crab Patreon, the subscription can like most other subscriptions be cancelled whenever you please and you get to keep the 0.11A version if you've already claimed it as a Patreon.
Another reason I wouldn't recommend you to pay again on Itch is that the 0.11A version will QUICKLY become obsolete. As Sad Crab updates the game with future 0.11BETA versions, the 0.11A version will be the worst option for anyone who has already paid once and terribly outdated.
Edit and TL;DR:
If you paid once it's a bad idea to pay again, the next 0.11B version will contain everything from 0.11A plus more, and you already own access to it when it drops.