Background

When a node has multiple private channels with the same peer, the hop hints in their payment requests will be populated with multiple channels. The purpose of these hop hints is to specify the next node's key and indicate the fees and cltv delta needed for route construction.

In pathfinding, due to non-strict forwarding, an LND node paying to this destination will only use the

Add something similar to the ActiveSubscriptionRequiredMixin mixin proposed by @ZachPerkitny in dj-stripe/dj-stripe#1091 (comment)

Ensure this is documented in the "Checking if a customer has a subscription" usage section and a mixins reference section of the docs

Would be useful to have deleteinvoice RPC method (opposite to createinvoice) to be able to cleanup expired invoices