You can use them when you visit Luna's home, Daisy's home, Katrine's home and Cayenne's home
That depends on when Leanne/Lyn gets banned, I don't know when that happened in your playthrough.
If you are feeling like you have been waiting longer then 2 week, make sure you have spoken with Lyn at Bunny Bites after she gets banned.
Or if you are using an old save from 0.06 or earlier it doesn't work.