Provided you properly care for your knits they should last you for a very long time. Here is the place to learn how to care for them.
If you are planning on storing your knits for awhile please follow these instructions. First give any piece to be stored an inspection to check for damage. Put any damaged pieces aside for repairs. Then wash and dry them. Carefully fold them and put them in storage. Lavender or cedar are great ways to keep insects away if your home has insect issues.
While your knits are in use you should avoid hanging them since hanging can stretch out the stitches and shoulders which can damage your precious knits.
I always recommend hand washing but some yarns can be machine washed. I will always include washing instructions with your item so you know what the options are.
Hand washing is really not as hard as people make it out to be. You will need a few things. Some wool wash. I use SOAK personally (I like the scents better) but Eucalan is just as good. Both of these have an unscented version incase you have a sensitivity to worry about. Fill a large basin or sink with lukewarm water. You will need enough water to fully cover what you are washing. While the water is filling your sink or basin pour in some of your wool wash. Both of my recommended brands have a measure of how much wash to use with different amounts of water. Once your receptacle is full carefully place your item in the water and push down gently and squeeze it to make sure it gets fully saturated with water. Then leave it to soak. DO NOT AGITATE YOUR KNITS WHILE THEY ARE WET. I usually leave my knits for at least 30 minutes, though I have left them for a couple of hours when I have forgotten about them. Next drain the water and gather your item in your hands and squeeze out the water. DO NOT WRING. This is very important. Just squeeze out the water. If you wring it you will stretch your knits and possibly felt it. It is best if you can support your entire garment while you are squeezing out the water. Once you have removed as much water as possible lay your knit on a towel and roll up then stand on it to ensure that as much water is out of it as possible. Many knits can just be laid out flat on a towel to dry. For socks, mitts, hats or anything with two layers I usually flip them over every 12 hours or so to help them dry a bit faster. Lace must be pinned out to retain its shape. If you are blocking lace I will include very detailed instructions but a brief version is that you lay out your piece on a surface you can put pins into (like a bed or foam boards) with a towel between the surface and the knit. Then you pin out the top edge following the line of the shawl. After that you pin along the bottom edge pulling the knitting taught.
As a note if you are local to me I will be happy to wash anything you have ordered from me for a small fee.
Anything that has been made with a superwashed wool or many synthetics can be machine washed. Anything that is to be machine washed should be washed on the wool/delicate cycle in cold water to avoid damage. They should also be washed in a lingerie bag so they do not get stretched out. If you are machine washing then dry in the machine as well in the coolest setting or on air fluff. When the item is damp dry remove from the dryer and dry the rest of the way flat on a towel.
If I have missed anything or you feel something is unclear please contact me.