curl --request POST \
  --url https://api.mnemom.ai/v1/billing/change-plan \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "plan_id": "<string>",
  "annual": false
}
'

{
  "updated": true,
  "plan_id": "<string>",
  "status": "<string>"
}