If you purchased a commercial subscription (and/or Telephony credits) inside your Bitrix24 account, you can find your invoice in PDF here: Subscription > Purchase History.
Only Bitrix24 Account administrator can view invoices.
If you purchased a commercial subscription from a Bitrix Partner (Bitrix Reseller), please request your invoice from your original Bitrix Partner.
If you purchased a commercial subscription and/or paid for a service inside a Bitrix24 MarketPlace app, please get in touch with the corresponding MarketPlace app developer.
If you are having any difficulties finding your invoice, or have any questions regarding your payments, please get in touch with sales@bitrix24.com (in your email, please make sure to specify your Bitrix24 account URL).