This is Klenty's daily email limit, and it cannot be increased.
If you need to send more emails, you can purchase a maximum of 2 email add-ons, to connect 2 more email addresses to your Klenty account. In this way, you would be able to send 500 emails/day, from each email address connected.
To purchase add-ons, please head to Settings > Billing. If you do not find this option, reach out to us on chat, and we'll assist you with this.