WordPress has over 60,000 plugins. The premium plugins shown here are some of my favorites.
ReviveSocial

Add a custom sharing schedule
Set a custom schedule and pick the days and hours when you want to share your blog posts. If you need more, you can even set different schedules for different social media channels.
Track every click
Both Revive Social plugins work with the most popular URL shortening services. This allows you to see how popular your posts are, and also track each individual click they attract.
Customize your social shares
Want to share just the titles of your posts? Or include a hashtag, or mention a @username, or some completely custom additional text? Revive Social plugins allows you to do that.
Share to multiple accounts
Operating at scale? Revive Social plugins allow you to share your content to multiple accounts on each of the supported social networks. No limitations.
$49 - $399
More InfoJetpack

from $39 / year
More Info What is Jetpack WordPress plugin?
Jetpack is a plugin suite which combines essential WordPress features into one large plugin. It allows you to manage the features you want to use, and you can turn off the features you don’t need.
Jetpack is a plugin suite which combines essential WordPress features into one large plugin. It allows you to manage the features you want to use, and you can turn off the features you don’t need.
WooCommerce

Free up to $249 for extensions
More Info Built to integrate seamlessly with WordPress, WooCommerce is the world's favorite eCommerce solution that gives both store owners and developers complete control.
Soliloquy Slider

The Best Responsive WordPress
Slider Plugin… Without the High Costs.
Over 900,000+ Downloads of the Soliloquy WordPress Slider Plugin.
$19 and up
More InfoCobalt Apps

varies up to $199
More InfoWP Rich Snippets

Add semantic / structural markup
Once your content is marked up, your web site will be more meaningful and accessible by search engines, your pages will be indexed and ranked more relevantly to its search queries.
Snippets
Enhanced search experience
If your pages are marked correctly, search engines may show rich snippets -detailed information- in search results. These snippets intended to help searchers with specific queries.
Traffic
Gain more web traffic
Rich snippets help web searchers recognize when your site is relevant to their search, and may result in more clicks to your pages.
$69 / year and up
More InfoAffiliate Royale

Affiliate Royale is a complete Affiliate Program plugin for WordPress. Use it to start an Affiliate Program for your products to dramatically increase traffic, attention and sales. Once you launch your affiliate program with Affiliate Royale you’ll be able to easily track your affiliates to see how they’re doing. You’ll see how many clicks they’re driving, sales they’re making and how much to pay them at the end of each month.
Even better, your affiliates won’t have to go anywhere but your site (with your look & feel) to login to their Affiliate Dashboard — because it will be seamlessly integrated into your website.
With Affiliate Royale you’ll:
Launch your affiliate program in a matter of minutes
Monitor affiliates’ clicks, sales and payments
Maintain your brand with your own Banners and Links
Drive more traffic to your site from your Affiliates
Increase revenue with more sales!
$85 to $169
More InfoCSS Hero

$19 to $69 / year
More InfoShipStation

Ship more in less time with ShipStation.
Connects with the most shopping carts, marketplaces, and carriers
With ShipStation, ecommerce shipping is easy - you'll be up and running in minutes — no installation or insanity involved. You’ll be able to do all of this and more:
Import orders from all your selling channels into a single platform
Create shipping labels and ship with 30+ carriers
Take advantage of incredible USPS and FedEx discounts
Sync order status and tracking details with your store and marketplaces
Promote your brand on notification emails, shipping documentation, and more
Manage orders and view reports from anywhere with ShipStation Mobile
Leverage Fulfillment by Amazon (FBA) and other fulfillment providers
New integrations and features added all the time!
Powerful shipping software with all the features you need
Customizable automation rules that easily manage repetitive tasks
Flexible workflows that increase order processing efficiency
User-level permissions and restrictions that give you full control
And it all works with your unique business requirements
$9 to $159 per month
More InfoCodeCanyon

All the code you need from PHP to Bootstrap, created by our global community of developers.
$2 and up
More InfoBarn2 media

$99
More Info Every WooCommerce site needs this plugin!
Beaver Builder

$99 to $399
More InfoSmash Balloon

$49 to $249
More InfoBackUp Buddy

$80 - $197
More InfoCreative Minds

$199 - $499
More InfoGratisfaction

Reward customers for promoting your campaigns through their social networks. Set & give instant rewards on signup goals.
Run viral campaigns. Choose your actions, rewards, rules & much more. Display on Facebook, website & mobile. Capture subscribers. Reward purchases.
Setup & reward actions & challenges. Get consumers to make purchases, watch videos, refer friends, etc. Reward these actions. Engage customers through gamification
Free for first 100 members
More Info A "Frequent Flyer" program for your website visitors!