Here is my product: https://matchkraft.com/. It is a marketing toolkit. I think you need to ask for feedback, asking why users don't want to pay for a premium subscription. So far, you are getting new users that is a good sign you are going to the right direction. Maybe, who is your ideal customer or maybe your product is ok but need more visibility (maybe paying ads). Try to get active users. I really want to... Source: 12 months ago

Calling a 3rd party API: There is a complete ecosystem providing "google-sheets-as-DB". I personally tested and recommend https://sheetson.com/ but there are a lot more with free tiers https://sheetsu.com/ https://sheety.co/. Source: about 2 years ago

Not OP, but have a look at [0]. It’s not great, but good enough. I regularly use it for App Store screenshots with captions and text. [0] https://theapplaunchpad.com/. - Source: Hacker News / about 1 year ago

For an advanced approach that includes localizations of your text and a ton of included resources to build your designs off of, there is AppLaunchPad (which has both a screenshot version and a mockup version with free and pay-by-the-month options), there is Vernissage which has a free and a pretty cheap pro version, and then there's App-Mockup which is free web-app. Source: almost 2 years ago

I used this. Paid for one month and got a good use out of it. https://theapplaunchpad.com. Source: over 2 years ago

I used AppLaunchPad. It’s a paid service but you can go monthly for single months when you need it (US$ 29). And you can easily wrap device frames for different size and colors of iPhone and iPad around the standard screenshots that you supply. Source: almost 3 years ago