The normal shelf life of mold silicone is 12 months if the lid is not opened. It should be used up as soon as possible about 6-8 months after opening.
For mold silicone that exceeds the shelf life, it can be used, and it usually shows thickening.
For the thickening phenomenon, you can stir until the gel heats up before use, and the fluidity of the silica gel will be restored at this time. But this batch of silica gel should be used up within 1 week, otherwise it will thicken again.