Long-standing client asked me to do her daughter's prom nails "as a favour" — third favour this year and I don't know how to say no anymore

Home-based nail tech, three years in. Have a lovely client, comes every three weeks without fail since basically day one, never cancels, always tips, genuinely one of my favourites.

She's asked me to do her daughter's nails for prom. Full set with art, so realistically two and a half hours. Framed as "you wouldn't mind squeezing her in as a favour would you, she can't really afford it".

Thing is this is the third one this year. Did her sister's nails before a wedding in March (free), did her own an extra time before a holiday in May at half price because she'd already had her set that month.

I said yes again obviously. Because she's lovely and loyal and I felt cornered on the spot.

But that's about £150 of unpaid work this year from one client, and I'm not exactly swimming in money. And now I'm slightly dreading her messages which is a horrible way to feel about someone I actually like.

How do you all handle this? Specifically:

- is there a script for saying no that doesn't damage a good client relationship

- do you have an actual policy (friends/family rate? one freebie a year? nothing ever free?)

- has anyone lost a good regular over starting to charge properly and was it worth it anyway

Feel like I've trained her to expect this and now I have to untrain her without losing her. Any wording that's actually worked for you would be genuinely appreciated.