Fbkca, thanks for the suggestion. We will keep this in mind for future updates.
Solution for you ( easiest one that doesn't deal with editing of .php code):
Note: instructions assume that you don't have a whole bunch of memberships and the description you are adding is not too long. Any custom code modifications done within the .html files will be erased if you update the software/plugin.
File that needs to be edited: ow_plugins/membership/views/controllers/subscribe_index.html
Code you need to add ( in this example code was added BEFORE <tr class="ow_tr_delimiter"><td></td></tr>):
<tr>
<th></th>
<th></th>
<th>description of your first membership goes here.</th>
<th>description of your second membership goes here.</th>
</tr>
Where 1 <th>'s should always be left empty.
Add more <th>'s to add description to your other plans ( if you have more then 2).
In this example we added description to VIP plan.
Result:
If you are not fan of editing .html files every time you want to change your description, then you can add new languages text keys in admin panel>>languages and edit .html only once.
If you are going to use text keys then the code will look like:
<tr>
<th></th>
<th></th>
<th>
{text key='membership+your_text_key_goes_here'} </th>
<th>
{text key='membership+your_second_text_key_goes_here'}</th>
</tr>
You can also add some .html code so that description extends/opens on mouse hover.
Ex:
<tr>
<th></th>
<th></th>
<th><span title="description of the membership goes here...extended version on mousehover test test test test test test">
description of the membership goes here...</span></th>
</tr>
Result:
You can play around with .html and css to make the end result look better.
Hope that this helps.