I wish my notes would always be deleted after 90 days.
Might even pay for it xD
Exactly!!
We have a spec for note expiration. Relays might already follow it - it's just missing in clients right now (afaik only NOS Social has it).
Expiration is different. The note expires for all relays. It doesn't allow you to send an expiring note now and later revert it back to non expiring when you move your notes from a free relay to a longer term storage.