What happen if verified trial expires?

No, it will upgrade you to the next highest plan.

And if you don't want it to do that you can set the trial length to 0 and no more verified trials will be created.

mm this not sound very good for me, so future user will not able to use the trial if I set the length to 0? How can I handle this?

They will be able to use your app. Your account will be auto-upgraded to the next highest plan.

ok but if I doesn't provided yet a payment method?

I misread your original question.

If you're on the free plan your account is never auto-upgraded. So, use a paying plan.