You can use internal and/or external benchmarks.
How did prior launches perform at your company? Are you choosing the right metrics? Use that as the benchmark to outperform by X%.
How are launches for similar products/features measured at a peer company of yours? What do their performance look like (assuming you have a network or a friendly willing to share). Use that as a benchmark. Do your investors have other portfolio companies willing to share?
Ideally, it's a combination of the GM, product management and product marketing. The GM would set the overall business goals for the year or quarter including revenue. The PM often drives the product launch adoption and revenue goals for that product. PMM often builds the plan with the metrics to help back into those goals.
The important thing is that if you see a gap, make sure that someone is owning all of these goals, otherwise, it will be meaningless to have launch metrics.
I think you’re asking if it’s behind a pay wall and not just a free product? If that’s the case, you need material (video!) that can act as a demo, people want to see product, not just read about it. Salespeople who can give great demos and free trials are often a really effective a launch tool.