As my app is an emulator, we know no emulator could play all games, however, the user side does not think like this way, some users find the emulator could play their games, they are happy to pay and 5 star rating, some users find the emulator could not play their games, they are angry and 1 star rating and request refund.
The AppStore will punish the developer and the app if 1 star and refund rate is too high.
So, I need the new feature, enable the users 1-7 days trial, each user has only one chance, once 7 days passed, the user could decide to pay or not to pay.
And, once he decided to pay, we should not allow his refund request any more, as he had already played the app 7 days, if he does not want to have the app, he could uninstall the app and not pay for it, however, he paid, he has no any reasonable reason to ask for refund any more.
And this new feature will be a big help for emulator apps.
I think all emulator developers will like this new feature, and will be happy to enable 7 days trial.
Anyway, the app will only need to be paid one time, so 7 days trial is good to go.
And the new feature will decrease the refund request, 1 star rating, as the user will not pay for the app, if he find the app does not deserve the money. So, no pay no refund.
I need the feature to avoid any non-users' refund request, they do not think my app is good enough, and I do not think they are my users too, they paid nothing, get nothing, and no pay no refund, I think 7 days is enough to make a decision whether to pay for the app.