Reward Potions are one-time use, but may be transferred between Sims by dragging from the Inventory to the other Sim. In most cases, unless you have a lot of Satisfaction saved up, the Emotion-specific Potions aren't worth it. Their buffs not lasting very long is the main problem, so ...
Most of them are secretory proteins routed either to the vacuole where they accumulate in large amounts in seeds, or to the cell wall and the plasma membrane. The structures of the members of the different plant lectin families are extensively described, but their function is somewhat puzzling ...