Every time you do a task in the game, you can earn a certain amount of Knowledge Points.
For example, in a POI you can earn one KP (more KPs if is in harsh environments). You can also earn KPs growing seeds, crafting, researching DNA. Every task has a certain number of KPs given, depending of the difficult level of the task.
You can also turn energy into KP. For this you need to check the option in your Player Profile. This option will decay your Energy over time, and every 2 hours (roughly) it will turn one energy into one KP.
There is no potion to increase KP earning.