Can I try iMyVoice for free ?

YES.

iMyVoice comes in two versions:
Monthly Subscription. First month is free. - iMyVoice contains all it's features and is updated frequently.
One time payement - iMyVoice contains all it's features and is updated frequently.

Bellow you can find AppStore links.

iMyVoice Lite

Contains basic and advanced features.

cost: Monthly subscription

iMyVoice SymbolStix

Contains basic and advance features.

cost: 79.90 $