Questions about store credit card error.

hi 老猫 and everyone,

Not too long ago, I ordered an item from a big store online, and provided all necessary info including payment, and scheduled to pick up at a local store. A few days later, the store manager called and said everything is ready to pick up. so I went there, requested a copy of the receipt, and took my purchase home. Several months later, I realized the store did not charge my credit card. still not as of today.

My questions are: Do I have a legal obligation to tell the store( charge me please)? Is there any legal issues I might face potentially? Is there any time limit for the store to have the right to charge me in the future?

This happened in Wisconsin.

Many thanks,