Or the tavern the NPC who sold you the cup rested the night before. I agree that you need to have some way to distinguish between the infite number of places the object might have been through over the last six month. Ways to play it:

1. Apply RAW and allows blind teleportation (pick up a cup and cast teleport)... you'll get 100% of the time... somewhere. I'd rule it's the place where the object spent the most time because it must be "taken from" there, so it must have some connection to "there". Heavily favors teleportation, I guess, and favors sillyness.

2. Require familiarity by another mean (even a description of the place) to pinpoint the target [favors Teleportation heavily and "grain of sand" [or strand from the servant's uniform] blackmarket]. Serious, but heavily favors teleportation. Acquiring an object that "have been there once" can be quite easy. Not my prefered way of ruling it because if you've been once to a place, there is a strong chance your wizard's staff, or your wizard's underwear, was there also. And "a place you've been very often" is very familiar (25% chance of mishap)... Nobody would use that if they could just cast Teleport using their underwear to propel their magic. Imagine the silly countermeasures, as well: "you would not part an old man from his walking stick?" "yes we would. Also, strip naked, old fool, before entering the king's castle".

3. Require the object to have spent at least six month at the destination (any amount of time would work, but since the link dissolves after the object has been taken for six month, it's reasonable to imagine that the link takes six month to establish, so an object moved from A to B for six month is either linked to A, then B, but not the two of them at the same time.). It's consistent with the examples given. Nerfs the RAW a little, but perfectly playable. Heck, my players will usually teleport based on description anyway and eat the damage in case of a mishap (and get back home if they failed to roll high and start again the next day). (My favorite take)

4. Not RAW at all... drop it. Teleportation had a fair chance of screwing people when it was a 5th level spell. Now it's 7th level, like the old teleport without error. I understand putting the spell later in the game to avoid scry-and-die strategies, but when they're spending a 7th level spell to move around, the players should get wherever they want. Whats the next step? Wish to be at the destination? (My second favorite take)

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