Share test organization between Zoho services

Share test organization between Zoho services

Hi there!

Our team uses Zoho Subscriptions API by test organization.
We want to use Zoho Invoice API for downloading pdf-version of invoices.
But we don't understand how we can share single test organization between subscriptions and invoice services.
Please tell me how we can generate valid api authtoken for Zoho Invoice using organization id from Zoho Subscriptions. 

Cheers,