Haven't gotten paid yet..? (Urgent!)?

Since you didn't discuss payment, she is under no obligation to pay you. Hopefully she will say, "And what do I owe you?" when you return the key but she may not.

I pet sat many years ago. I thought everyone in the neighborhood knew I charged for my services. One lady and her family were gone for a month. When she came back, she said "Thank you." When I asked about payment, she reminded me that we had never discussed payment and she had thought I was doing it to be a good neighbor and friend. There was nothing I could do. Another family brought me their four guinea pigs when they went on vacation. We had discussed payment. They never came back for them. When I finally found them again, they told me that they didn't want the guinea pigs back and I could have them plus their food and cage instead of payment. When I protested that I didn't want 4 guinea pigs, they pointed out to me that minors can't make contracts. Unless you are of legal age, she can stiff you for the money and suffer no consequences.

I think you've learned a good lesson. I'm sure you'll get paid eventually. I have a retail store and my people take orders all of the time. We won't process an order without payment in advance (especially custom work). This is "finance, not romance".

You shouldn't be sitting any dogs other than your own unless you're a licensed/insured and experienced sitter, that has a written contract signed by both parties.

"How should I address this is she doesn't pay me tomorrow?" Chalk it up to a learning experience and do things properly the next time.

Her prerogative to refuse to pay you, and you only have yourself to blame for not doing things properly.

"I did her a service which is EXPECTED to be paid for." Only if your have a written contract and/or a reliable witness to a verbal contract.

While I agree that you have agreed on payment BEFOREHAND it's not like a friend that's returning like favors to you so she SHOULD pay you.

Just say something like "I really need to pay my cell phone bill" or something like that and then "Could I get the money you owe we for pet sitting?" That would be pretty screwed up if she thought you would do that for free.

You should hint about gas, maybe something like

'Wow, the gas prices are rising, it cost me a fortune to get to your place!'

and hopefully she gets the point and remembers to pay you.

I would be like yea it took alot of gas for me to drive out here and watch them but they didnt cause any trouble

You probably should have considered asking her about payment first. Since you babysit for her frequently, she probably thought it was just a favor or somehing....