LSD is pretty sensitive to the environment, if it is kept in a hot area and is exposed to a lot of light it will degrade fairly fast. I know someone who left some sheets in his car over a few days at a festival, and he said it was really hot and exposed to sunlight. They told me that it felt like its strength had been cut in half after only a few days. If you keep it in a cool dark area it should last for a couple of years probably, I have never kept it for so long without using it all up but have stored blotter in amber vials in dark drawers for nearly a year and it kept good. I used to put it in vials in baggies filled with moisture and oxygen absorbing material and freeze it but it isn't worth the hassle imo because even in a dark drawer and baggie it will last for many months to years. In non-distilled water it will take a huge potency hit because of trace chlorine, but in distilled water it can last for at least a few days maybe more. Stored in alcohol solution in cool dark places it can last indefinitely, people have used decades old LSD that had been stored in these conditions. Pretty much if you keep it in a cool and dark area you can expect it to last for at least several months and realistically it will probably last for years before it degrades much. If you keep it in warm or hot places and/or expose it to light then its life expectancy can be much shorter.