Personally me, I struggled with registration. Probably you can increase conversion of registration adding google, facebook and/or other SSO. I`m struggling with that too)
I couldn`t try the app it because there is no free trial. I have 2 products 1 with trial and second without, and for sure, without free trial people do not purchase. We can chat with you about how to prevent cheating with free trial
Then, for me was unclear a plan with my own key. For sure, I`m a dev, that`s clear for me, but not for final user , who is not technical person, but wants the cheapest option. Also you have only 2 rate plans - 1 mnthly, 1 annual. Maybe you can test with adding 1 smaller and 1 bigger usage plan? Just to verify a concept? Several rate plans are working perfectly for me personally.