Memories are also for Scholarship if you can find a scholarship station. If you want to think Short Term, the only place you know you can spend memories on right now is the Goblin Crafter at the entrance to this dungeon.
Hmm, well there's not all that much handy with the goblin. Other than potentially gaining a golem minion if we decide we want to go all-out commander style or something (we do have the materials for this, and it takes any three memories - which means that this could be of any type but it'd grab them all).
Looking at scholarship, we currently have one (F)rustrating and one (C)reative memory. Those can be invested in Shop (accepts all memory types), Literature (accepts Creative of the ones we currently have), Life Sciences (accepts Frustrating of the ones we currently have), and Algebra 1 (accepts Frustrating of the ones we currently have).
Gaining a (T)riumphant memory would give us the option of Communications or Physical Education. Gaining a (B)urning memory would give us the option of Algebra 1 or Physical Education, and we can already add to the former. Gaining a (F)rustrating memory would allow us to invest a second time in the Frustrating-accepting options above.
Shop is not likely to be useful at the moment since the crown is de-artificing us, though we'd need to invest multiple times to jump a class level in Artificer anyway. We can also use two sources of wood instead of a memory.
Physical Education grants us +1d2 max HP for every grade we jump it, which is useful but probably out of reach since we can only invest in it once right now.
The tutorial scholarship station claims we can't invest in Literature right now since we already did that once, and even with heavy investment our current grade of D+ will take some time to get to a B, which would bump up our Epic Bard class level.
Algebra does not seem as useful, as bumping its grade up gives a scroll of addition which adds +3 to our next d20 roll. Life Sciences grants a scroll of dissection which lets us gets more resources off fallen enemies, which might be handy.
I am not going to commit to a decision just yet, but I'd propose a Triumphant gain. Looking for feedback from other players too, feel free to chime in!