[RandomLensman]

You can at least start from the top: the overall thing you are working on, how much did that make? Are features you worked on a contributing reasons for a sale/how much extra did they bring? Are you directly linked to some sales because you provided something specific? If you are doing internal software, could be cost reductions associated with that or also additional business.

Your number won't be exact, but it doesn't have to be and double counting among the other people isn't always bad.

[Scarblac]

I make frontends for our products (that we sell to governments), but they're not what drives sales. Customers by our product got features of the backend, they assume there is some frontend. If I do good work users are happy, but they don't make the buying decisions either.

That I work on the front ends was only partly my choice, we all move around depending on where we need people at that time, and other people decide what needs to be implemented.

If we were to fire all developers, we would probably lose hardly any sales the first year. But over time, licenses would go down more and more. So part of this year's profit is due to the work of people who left us years ago.

I don't see any point in claiming some specific part of our profit. People would laugh at me, probably.

[RandomLensman]

You don't need claim, but you can at least associate with it. Even tracking happy users is a measure of sorts. It isn't an exact science and it doesn't need to be. And, yes, that isn't always fair to those gone from the company.