my question is that
is this guaranting that this file will always exist in IPFS forever?
Or
is it removed from IPFS 6 months after the last access?
If the latter case is correct, should I use the “api/v0/pin/add” API if I want to keep the file persistently in IPFS no matter when that file is accessed?
When you add some content, you add it to a specific node (or Infura), you don’t add it to IPFS the network, and thus there is no guarantee that your content remains available if you don’t make sure your node is still there with the content. You have to keep your content pinned in order to not have it removed. The IPFS 6 months after the last access doesn’t apply as of now.