As the keyboard lubes are liquid, they tend to dry out with time, no matter whether those are high-quality or low-quality lubes. But the drying-out speed depends on the quality of the lube. Because, the low-quality lubes will dry out fast, and high-quality ones will dry out a bit slowly.  But you can apply some methods to slow down the process of keyboard lube getting dried out. Try cleaning the dust off the keyboard regularly and maintaining a lower temperature in your workspace where you keep the keyboard. Also, if you are able to choose a high-quality grease-type lube, it won’t dry out quickly.