You can still re-download any packs which you've claimed on itch. For this pack, I would have to give you a key manually and then you would be able to get future updates, yes. For most other packs, it's more automatic- You connect your itch/Patreon accounts, find a pack you like here, click the patron-only link, and it should be added to your itch account. This pack works differently on itch's end because of the way it's set up as a free/paid hybrid. On Patreon, I believe once you stop being a member then you would lose access to the downloads from Patreon, unless you had specifically purchased the pack there, which is also possible.