True they won't kick you out, but it is a wee bit rude to not at least spring for a cup of coffee or tea and occupy their space.
I go here all the time to study and I've never been kicked out for not buying anything. You're good.
They won't kick you out for coming in to study without buying anything, but they don't want outside drink brought in. There have been many accounts of people bringing Starbucks drinks into the shop.
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