Why not purge notes older than a month?
nostr:nevent1qqsyd4rugvhx8swr9u9r7jaycp3kq64xkg7xxa9vv6k63v80ra65gpcppemhxue69uhkummn9ekx7mp0qgsr9cvzwc652r4m83d86ykplrnm9dg5gwdvzzn8ameanlvut35wy3grqsqqqqqp4hppdx
In my unterstanding it is, because the notes aren't stored. They're only transferred. So there is nothing that can be deleted.
