<p>I am at the point where I need to add keys to my app. What are some of the possible solutions you guys used? I've looked at an earlier <a href="https://stackoverflow.com/questions/118031/best-activation-key-software-for-net-application">post</a> so far, anything else before I decide. My 2 influential factors are:</p>

<ol>
<li>Price</li>
<li>Ease of use</li>
</ol>

<p>Thanks</p>

Aladdin
Aladdin's Software and Hardware Solution Comparison Chart
We purchase these keys and they are very easy to use with sample code generated for you from their utility.  Added to this is they are a very professional company (no I don't work for them but have used their products in 2 different companies)
The basic hardware keys themselves cost around $30per in small qty but you must purchase the "Master" set which is more expensive (at this time I can't recall the cost).