Hi.
This worked for me:
last_expense:
friendly_name: Last expense
unit_of_measurement: €
value_template: >
{{ state_attr('sensor.curve_email','subject') | regex_findall_index("€\d+.?\d+") | replace(" €","") | round(2) }}
attribute_templates:
seller: >
{{ state_attr('sensor.curve_email','subject')[27:1000] | regex_findall_index(".* on") | replace(" on","")}}
Can you explai how you created your expenses card?