Thank you for your feedback. You can do a lot with the app, for free. The subscription offers some extra features at a small price (2$/month or 12$/year) and helps me pay for the backend servers costs and ideally it will provide a cashflow to continue investing in it. You can do a lot without paying anything. Using the promo code doesn't require a subscription, it is like a paid app, but free. After the promo code expires you can still use most of the features of the app. Would you be more inclined to pay let's say 25$ for the full feature app without having the chance of testing it?