Easy. Any temple-type (Aribeth and priests) or shopkeeper can help. Ask for temple services or to see their wares. Their stock will appear left and your inventory on right. Press the eye icon near the lower left of your inventory, press "OK (I'll pay 100gp)" and voila! When you get Potion of Lore or the ring of a similar name, they will sometimes work and sometimes not, but without gp cost.
Also, items backgrounds are color-coded: white for usable, red for not usable in your current character configuration and blue for unidentified.
