Apply one-time next-month discount on Subi customer contracts

We want to be able to add a discount directly to a subscription customer contract that applies only for the next month (next order) and is valid just once, not every month.

Right now, discounts with an order limit cannot be added to a customer contract, so we have to manually remove the discount after the next order goes through to ensure it does not apply more than one time.

This would reduce manual work for us and help avoid customers receiving the discount for more than a single renewal.

If this would be helpful for your store as well, please upvote this request!