would costco let you in if you use someone else's costco card?

You might be able to make it in the actual door, as you usually just have to flash the card to get in; however, upon check out, only the cardholder can make a purchase.

If you have a Costco Cash card that you have received as a gift, you are allowed to enter Costco and make a purchase without being a member. Costco Cash cards are available in denominations from $25 to $1,000.

Additionally, you do not need to be a Costco member to use the Costco pharmacy. If you would like to make a purchase at the pharmacy, you would let the Costco employee at the entrance know that you are heading to the pharmacy, and they will let you in.

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