Check data in Subform then change field in another module

Check data in Subform then change field in another module

Hello,

Zoho One user here.

We would like to know if our customers have purchased a service contract from us every month. I have a custom module that has data imported to from Xero (our accounts software). This custom model has a subform with each item on that invoice, An account could be linked to many separate invoices. Ideally I would like to have a pick list in the account that states "Under contract = Yes" if the invoice has "CONTRACT-SUBSC" under "Item" in the subform, with an option "Yes (override)" & "No (override) to be ignored by the script. This only needs to search invoices created within the last 31 days for that said account.

I can't see how this is possible. Any assistance would be greatly appricated.