Likelihood of Likability

From my experience, I've found it best to treat likeability potions like any other gift item, taking stress into account. So make sure you check their mood and "refresh" the NPC if necessary between batches.

yeah, the info makes it sound like it's always going to be that number & that you just gift them the amount of pots & they'll give you access to their shop, but they do get stressed from it. with agnes, she only needed 5 or 6, but i did use a keyword with her before gifting. with nora, she needed the exact number listed, no keywords at all. with gordon, i've gifted him the 7 that's listed, but he still won't grant access. it seems like memory helps in cases with ~5 pots so npcs don't get stressed after receiving the same gift repeatedly & that likeability pots DO stress them out to the point where 7 pots in succession & a keyword won't get you access