maksbd19

This plugin will add a custom post type for event. In that you will be able to add/edit/remove events just as you do to your 
posts. There are 9 parameters are by default supported. These are-
<ul>
<li>Event date</li>
<li>Event Duration</li>
<li>Offical Website</li>
<li>City</li>
<li>State</li>
<li>Country</li>
<li>Event Gallery</li>
<li>Event Categories</li>
<li>Event Tags</li>
</ul>
And also you can add title, description, featured image to your event.
In the widget you can specify the title, maximum height of the widget, number of events to show and to display event from a 
category or tag.
Event state, city and countries are included in the search parameter. That means if someone search anything that matches with these 
meta values, they will show up in the search results.

Event Management Plugin

This plugin will add functionality in your site to add/edit/remove events and display them in a widget.

thesiim

Create and manage online registrations with ease. Design your own registration layout and manage bookings.
SeatReg is a plugin that offers the following and more to build and manage online registrations.
<ul>
<li>Map Builder: Design your registration layout with a versatile map builder. Easily create, delete, resize, and move elements. Add prices, legends, seat numbers, hover text, customize colors, and more.</li>
<li>Registration Overview: Get a overview of your registrations. Track the number of open, approved, or pending bookings.</li>
<li>Customizable Settings: Control the booking flow with numerous settings. Create custom fields to collect additional data from customers.</li>
<li>Email Templates: Utilize customizable email templates.</li>
<li>Export: Export bookings to different file formats (PDF, XLSX, TEXT).</li>
<li>Calendar Mode: Manage bookings with an integrated calendar mode.</li>
<li>Responsive Registration View: Provide a scrollable and resizable registration view via a direct link or embed it into your website pages using a shortcode.</li>
<li>Payment Integration: Support for PayPal and Stripe payments.</li>
<li>Coupons: Create coupon codes to offer booking discounts.</li>
</ul>

SeatReg

Create and manage online registrations. Design your own registration layout and manage bookings.

Event Management Plugin vs SeatReg