zackdesign

Paypal API Subscriptions is designed to allow your users to register on your blog and subscribe all at once. 
The Paypal API keeps them on your blog and means that you simply have to skin the WordPress Admin to suit your 
site theme. Because it is fully integrated with WordPress you can keep track of your users easily and effectively.
This plugin defaults to the Paypal Sandbox for test results so you can test it for yourself.
You really need SSL before you can begin to think of using it for real. Download Admin SSL here: <a href="http://www.kerrins.co.uk/blog/admin-ssl/" title="Admin SSL" rel="nofollow ugc">Admin SSL</a>.
It’s important to realise that you won’t be able to test Express Checkout until you use your own developer API credentials.
Features:
<ul>
<li>Subscription button shortcode tags for your posts</li>
<li>Use your Paypal API credentials</li>
<li>Integrates with WordPress registration seamlessly</li>
<li>Use a WordPress Admin Theme to make the user transition completely transparent!</li>
<li>Adheres to all Paypal Guidelines and Requirements</li>
<li>Uses WordPress-supplied error checking in the registration form for both transactions and fields! This means no registered users by accident.</li>
<li>WordPress-MU compatibility!</li>
<li>Automatically tests using the Sandbox SDK credentials </li>
</ul>
List of possible future features:
<ul>
<li>Ability to cancel subscriptions directly inside WordPress</li>
<li>Further Paypal Profile changes</li>
<li>Additional subscription stuff like initial payment and trials </li>
</ul>
Need help? Contact me at <a href="http://www.zackdesign.biz" title="Zack Design" rel="nofollow ugc">Zack Design</a>.
Please be aware that I’ll only be updating this if I need to or if I’m paid to. Feel free to come on board and contribute!
<h3>Latest Changes</h3>
1.0
<ul>
<li>First release!</li>
</ul>

PayPal API Subscriptions

Provides an all-in-one registration point for subscribers to your blog. Uses Paypal API and recurring billing.

kdiweb

Onscribe allows everyone to launch a subscription service with multiple providers from their WordPress site.
Whether you’re a blogger or an artist, you work hard producing your content. And although it may be a labour of love, you deserve to be rewarded for your efforts.
Onscribe takes the pain out of setting up payment gateways and makes it a snap for you to add subscription buttons to your site, blog, app or online game, so all your fans can actively show their support in a meaningful way.
The WordPress plugin is designed with ease of use in mind, making it easy to include subscription buttons anywhere on the site through the use of shortcodes.
A few highlights of the service:
<ul>
<li>Simple integration with WordPress</li>
<li>Secure processing using major third-party payment providers</li>
<li>All inclusive UI for both publishers and subscribers</li>
<li>Extensible through API</li>
</ul>
Like WordPress, Onscribe is people-centric and wants to give more power to its users.

Onscribe

Add subscription buttons in any Wordpress blog with this simple integration of Onscribe.

PayPal API Subscriptions vs Onscribe