To think my friend is ungenerous in only buying herself a concert ticket?

It sounds like you’re good friends & if she’s socially awkward she may not realise she’s offended you. Talk to her & tell her how you’re feeling.

Talk to her!
Did you, either last year or this year, say, "Sounds like fun! Could I join you?" and get fobbed off?
Or has this awkwardness about whether or not you can invite yourself along kind of crept in?
I think she's maybe taking your vague "depending on the finances" comments to mean that you're just not into the bands she now likes going to see.

She is rude to not ask you if you would like to go with her but not unreasonable not to pay.

My long term friend lives in the opposite end of the country and comes to stay once a year. Likewise I stay with her once a year.

So the two of you trade off equally going to stay with each other (for multiple days it sounds like) once per year each... that sounds fair and reciprocal.

During her last turn to come visit you there was a concert she wanted to go to on her own one of the nights. This cost you nothing and the two of you had your normal visit the rest of the time. Do I have that all correct?

Honestly it doesn't seem like she's using you at all unless you've left out the part about you paying for both of you to attend gigs during your turn to visit her. She doesn't need to "pay you back" for having her stay with a concert ticket because she does so by having you to stay in equal turns.

It's very normal and reasonable when a friend comes to visit for several days to have a day or evening when they do something off on their own amidst the time you spend together. That's not the same as her treating your home like a hotel or freeloading.

I think its weird that people are saving you are saving her money, and she's using you as a free hotel. The visits are reciprocal, and since when did we start thinking that having friends to say was something so transactional.

Of course you should just ask her why she isn't inviting you.

My friend moved out of London and as far as I’m concerned my house is open to her whenever. She stays with you for five to seven days, so she’s going to a thing but then you get to hang out with her? I’d never expect my friend to by me a ticket to whatever she was going to which is why she’s in town if I couldn’t afford it, I might be jealous but I’d also just be glad to see her.

If she a good enough friend for you to host for so many days why can’t you talk to her about it?
Surely your simmering resentment is eventually going to kill the friendship otherwise, if you like her as a friend you have to address this.
Do you worry that she doesn’t really value the friendship anymore and you’re just convenient free accommodation when she wants to visit the area and catch up with other friends?

Text her back to say that you can't afford to host her & send her the link for a premier inn. Cheeky cow, she's not into the friendship & is just using you for free accommodation.

This
maybe as you don’t mention it @LoisLaneKent they she thinks you don’t like the band or want to go

Are you ok with that? Also why is she wanting to say that long? I Thought she wanted to see a band so 1 night is all she needs if you really want to allow that.

if it’s £50 and she expects to stay 5 days she should have bought you a ticket as a thank you for the accommodation. I’d tell her that it’s not convenient for her to stay with you. She’s taking the piss.

Did she invite herself? Will she cook? Pay for food? Take you out for a few meal’s?

I wouldn’t expect a free ticket but I would not of agreed to let her stay at my Home for that long.

So is she going to these gigs alone?
Or with other people?
The latter would seem much ruder than the former.

She is using you for accommodation. Just say no.

You don’t have to be friends with someone who uses you as a convenience/airbnb. Sounds like she’s not thinking of you as a friend or someone to enjoy an experience with, but as someone who conveniently lives near a concert venue, and has previously allowed her to stay for free.

This would be her last free ride.
I'd probably cancel anyway, she can book a hotel for the event.
Don't visit her again.

I wouldn't expect her to buy you a ticket at today's concert prices, however you also wouldn't be unreasonable to tell her that it's not possible for her to stay this time.

Yeah 50 she should be buying you a ticket as thanks for staying, no doubt.

Is it possible she's having money trouble though?

Does she go to these gigs alone or with other friends that live in your town but don’t put her up?
I think if you both visit each other regularly and the host provides the food and drink when you do then that’s fair enough.

It's odd to not invite you when she is asking to stay with you.
Can't imagine going out all evening at a gig you'd enjoy, leaving you behind, then crashing back at your house! The cheek of it.

Exactly my thoughts!

OP why are you assuming she owes you a ticket?
You have said she is socially awkward, so I would take her saying she wants to come your way to watch a gig plus asking if she can stay with you as her way of trying to arrange for you both to go together!
She asked in advance and then eventually bought her ticket. I am assuming you didn't buy yourself a ticket because by your own admission you couldn't afford it, yet you feel put out that she didn't buy you one? Why should she?
By your own admission again, you said she looked after you well when you visited her, so, I can't see that she is overstepping in any way by asking to stay at yours this time. You said you otherwise have a great friendship so you should be happy to see your friend for the few days she will be there. Don't begrudge her going to see a band that she has been looking forward to simply because you didn't save up for your own ticket.

One night's hotel would equal a ticket tho. So she won't lose out by buying a ticket for her friend. It'll work out at less than £10 a night. Bargain!

She is sooo cheeky!! Even if she wasn’t paying for your ticket, just inviting you along Would be just something that you do with a friend, especially if you want to stay at their house.

Don’t let her stay, make up an excuse - maybe then she will realise that she should treat you better!