Songs that are licensed can have very short or very long life spans depending on several different factors.  I've written songs as far back as 11 years ago that are still used every year and that I still get paid for. 

I've had other songs that I wrote over five years ago not be used at all, and then all of sudden show up on tv show last year and ended up being used over two dozen times.

I've also had songs used once and then never used again. 

Some of this is just timing and dumb luck, but there are other factors to consider when it comes to the potential life span of a song.

Here are a few...

Style
Does the song sound timeless or is it stylistically tied to a certain "sound" and certain era?  Some songs have a very specific sound that is connected to the time frame in which the song is written.  Different trends come and go and if your music is very connected stylistically to a very current sound it might have a shorter life span than a song that is more stylistically "open".  For example, guitar and vocal songs worked fifty years ago and they still work today.  Some styles never completely go out of style.  On the other hand, a style like grunge or disco isn't nearly as popular today as it was during their respective heydays.
 

Subject Matter
Another consideration when it comes to the potential life span of a song is the subject matter and lyrical references.  Do your songs reference current events and things happening in current pop culture?  These sorts of references can work great, but they can also limit the relevance of your music a few years from now.  I always suggest when writing for licensing opportunities to keep things as broad as possible in terms of subject matter.  Themes like love, break ups, pain, moving on and so forth never go out of style.  These topics are just as relevant today as they were in the 60s, 70s and 80s.  The broader your subject matter the more potential opportunities your music will work for.

The one exception to this rule is if you are asked to write about a specific topic or specific them.  Then of course it makes sense to write about something more specific. Sometimes supervisors are looking for very specific lyrical references to fit very specific scenes.  Maybe they need a reference to a specific city or a specific person's name.  This actually happens a lot.  But I personally don't try and write for all these potential scenarios unless I know about a specific project.  Otherwise it's sort of like looking for a needle in a haystack. 

Do Supervisors Like Your Music?
Another situation that can arise is when a supervisor just happens to really like your sound or style.  Sometimes supervisors have artists they simply like more than others and use their music repeatedly as a result.  This of course isn't exactly in your control.  But what you can control is the quality of your work. 

It's probably beyond obvious to state that you should always strive to create the best music possible, regardless of what style or genre you're writing.  In all the interviews I've done with publishers over the years I've been consistently told that most catalogs have a small percentage of artists, five to ten percent,  that end up getting the majority of placements.   This really comes down to the quality of music and the quality of production. 

Good music rises to the top.