Trail membership 30 days only apply coupon code

Hello team,
I want guest user member ship in my site and I want coupon code is mandatory filed in free membership of 30 days trail.
But I’m not able to set configuration can you please help me asap.

My Site url: http://koolchord.hyperbeans.com/backstage-pass/

Thanks,
Hitaishin

There’s no way to force a coupon code to be used (without custom code which I’ve never personally written), but if you create a shortcode with a charge for the trial period and a coupon for 100% off that charge you would be, in effect, requiring a coupon for a free trial.