In general keep it dark and rinse your reel with fresh water and it should give you a couple of years if you are boat fishing. If you are casting it depends on how many birds nests you get or the sort of ground you are casting over, I would change line at least once a year for casting.
I moved up here 20 years ago. I bought a good boat rod and a Diawa SL175H reel and a bulk spool of good quality line. I had a creel boat for a few years and used the gear to catch bait (As you can imagine it was just left on the boat covered in fish scales etc). I then put the stuff in a shed for about 13 years and only took it out when I bought a small angling boat. The rod lost its rings and reel seat, the reel died last year but the line is still going strong and I have it on my new reel and I still trust it.
Unfortunatly the paper on the side of the spool of line rubbed off so I don't know what make it is.
Ultraviolet radiation that sort that causes skin cancer also deteriorates the molecular structure of nylon monofilament fishing line.... especially if it's exposed to sunlight over a long period of time.
Avoid storing line where it can be exposed to light or heat.
I generally change mine aprox 3 times a year depending on what type of fishing I have been doing, If I have a few outings fishing into rock with the usual lost bits of tackle then I generally re-spool the line onto another reel and check with my fingertips as i re-spool it back onto my reel to feel for nicks or abbrasion on the line, also this reverses the line so you get to use the bottom half.