Hi,

For subscription products, You can include time-based pricing for some things depending on the demands of the business. For example, you might base payments on the number of hours, days, weeks, months, quarters, months, and years that a product was utilized.

For more details, refer to the blog:
https://www.cybrosys.com/blog/how-to-manage-subscriptions-products-and-subscription-plans-in-odoo-16

Hope it helps

Nothing out of the box. 
One client decided not to migrate to v16 because of all the other functional breaking problems with v16 subscriptions. 

One other client we have custom developed a module with the necessary flows to handle this as "credit" and auto apply it during the invoice cycle. 

You can think of it like a "giftcard" type of credit. 
So the discount becomes a credit which is available until "consumed". 
During invoice cycle, we check if the customer has a credit available, if yes, we consume it on the invoice. 
If not, then nothing happens in terms of discounting. 
So the credit gets applied during first approval of sale order and on the first invoice, which makes the credit immediately back 0/zero/empty so there is no more discount for renewal invoices. 

It's a "stupid" method if you think of it like this as workaround, but it does work just fine and we are using mostly existing pieces from Odoo via loyalty program. 

Did you find a solution for this?