I had them out of a fridge after opening for about 3 months and then they were fridges until used. Seemed fine. As you say the sugar content should keep them good. Just to be safe I will keep next jar in the fridge
Quite a good drink this. Like others say it has a candy-like lightness to it and the gin, Tanqueray 43% (old school) really comes out. Probably worth trying again with another gin to see how the flavours of that gin are brought forward. The saline also helps bring some flavours out.