‘free trial’ text

I want to change the text that say ‘free trial’ to something else. Can you please help me and point me to the right direction.

Btw, I google and saw this code but it doesn’t work on YITH Subscription:

function wc_subscriptions_custom_price_string( $pricestring ) {
$pricestring = str_replace( ‘every 3 months’, ‘per season’, $pricestring );
$pricestring = str_replace( ‘sign-up fee’, ‘initial payment’, $pricestring );

return $pricestring;
}
add_filter( ‘woocommerce_subscriptions_product_price_string’, ‘wc_subscriptions_custom_price_string’ );
add_filter( ‘woocommerce_subscription_price_string’, ‘wc_subscriptions_custom_price_string’ );

Thanks in advance