Is a principal's FPOA issued in one state, valid in some or all states?

This made me think about the DPOA document itself because it was approved in one state and would have to be sent to the office in another state. It works for business within the account holder's state of residency. It is not clear if it's a legal document honored across state lines. I would like to know if state specific documents are required or if a more generic FPOA form is available for disputes that cross state lines.

Hospital patient disputes a charge from a computer/anti-virus subscription vendor. It was a renewable one year contract that allowed an automatic bebit once a year. I asked how "one year" renewal option was deemed to be a "life long" contract. Vendor agreed it didn't mean life long.

As FPOA I contacted the credit card issuer and the vendor. Vendor suggested closing the account that it was billed to/open a new account to keep the vendor from charging in the future. Account owner (the patient) does not want to cancel/reopen her account. She wants to cancel the vendor renewal/charges.

This issuer was able to handle this without the FPOA document because 1) the account owner's conversations with both the card issuer and the vendor a month ago provided documentation to establish the customer clearly wanted to cancel 2)The vendor's failure to cancel essentially authorized cancellation by the card issuer 3) FPOA (me) was clearly working on behalf of the account owner 4) FPOA was not attempting to put additional charges on the card and 4) The subscription was in fact yearly so the authorization a year earlier could be cancelled.
The lady is trying to recover and said she doesn't have the energy or patience to deal with the vendor -but she knows what she wants!