Leather Sofa Conditioner Recommendations?

I bought a couple of leather sofas (from SCS) about a year ago. I don't know what type of leather it is, but the finish is dark brown, with the surface texture not completely smooth - it has a network of little lines all over it, much like the skin on the back of my hand when I look at it closely.
They still look like new but I'm told that they wont stay that way unless I look after them. This apparently includes applying some sort of cream or conditioner, maybe twice a year.
Can anybody recommend a product for this job, or offer any other hints?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.