The leather in your Subaru is Wollsdorf Passport leather from Austria - it is some of the best in the world. It is Aniline corrected grain leather, the hide of an animal and has to be cared for to last.
The 3 main enemies of leather are:-
1. UV rays from sunlight
2. Perspiration from human skin
3. Dirt and soiling
How to prevent these 3 factors occurring?
1. Always try and park your car in the shade as much as possible, and have a garage for it at your residence.
2. Never sit on leather seats without your shirt on, and avoid wearing shorts as the under part of your upper leg is in contact with the leather.
3. Clean your seats regularly with neutral soap and water, and apply beeswax-lanolin based conditioner. (Neutral soap is soap like Sunlight Soap available in Super markets) and will save you a lot of money!
The suns UV rays cause the leather to dry out a crack in time. The perspiration also has the same effect, but even more so (It will even make vinyl go hard and crack up as well) and because leather is a porous surface, the pores clog up with dirt if not cleaned and it can't breath,so breaks down.
NEVER NEVER NEVER use any leather treatment product that has silicone in it.
The safest to use is Connolly Hide Care (Jaguar Hide Care), or Pelle leather cleaner and conditioner. These are beeswax, lanolin, water based as they do not contain Silicone.
All leather manufactures strongly advise avoiding silicone,as it clogs the pores of the leather and causes it to break down in time.