Heroku - Backend server hosting - $7 Cron To Go - Heroku add on for cron jobs - $9 Approximated - Handle unlimited custom domains - $20 Vercel - Indivisual site hosting - $20 Rewardful - Affiliate program - $30 Digtial Ocean - Spaces for some image hosting - $5 Upscribe - Email marketing and drip campaign - $9 Splitbee - App Analytics and email automation - $32 GSuite - Two email accounts - $13. Source: about 3 years ago

You can even use custom embeds! Notion includes multiple of these by default such as Google Maps, Typeforms, or tweets. Embeds make just about any custom html possible. I used this upscribe embed form below to handle early access sign ups for the service. Source: over 3 years ago

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: about 1 year 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