Ecash sat is a universal access token for relay servers.

“Initially, we thought of having relays issue one-time anonymous access tokens that users could purchase and use for anonymous pay-per-use. Later, we realized that using Bitcoin ecash as postage for messages would be a better solution.” nostr:note1h895va2vdwscyl3r339pdwnvy83kdu0cl646dnal69ws2n2s6p2qx2gaaz