If you do not prepare milk kefir drink, the seeds can be stored in a non-metallic container in the refrigerator crisper compartment, in a sufficient amount of milk to covered all the seeds; in the mean time, make sure to leave them some space so they can have enough air.
You can also dry the seeds on a clean linen in the open air, simply by covering them with a muslin so that dust doesn’t penetrate. This way, you can store them in your kitchen cabinet, in a jar covered with a muslin retained by an elastic. In order to later reactivate the dried milk kefir seeds, simply soak them a few hours in lukewarm water (do not use hot water).
Another solution consists in freezing the milk kefir seeds and then let them thaw in open air.
Please notice that the dried milk kefir seeds and the thawed ones usually take longer to reactivate, so you have to be patient.