Dynamic Master Table - Lifetimes

Hello everyone

I have a conceptual question of data model or of finding the dax formula that reports the correct data. In the case of a master table (in this case of products), which have a date of discharge and date of discharge, how is it possible to find the number of products in force for each day?

I've set an example that so you can easily understand me. It is about finding the % of products sold on the total of products existing in the master to date. I have tested with many-to-many relationships, with userelationship, with the help of calculated columns and I still do not understand how the whole model should be mounted and related efficiently. In the example I performed the calculation without having to have the validity of the products.

Any questions you tell me. Thank you all so much for the help.