a web app developer

I'm using a Hubspot CRM, and I already have a custom customer self-care portal. It works fine, there's nothing to do with that. But I'm running a fruit and vegetable delivery business and I need a web app for my couriers who are delivering the goods (baskets) to my customers. They will get the customer's information with this courier web app. The courier web app is fed from my Hubspot CRM database via API. A question here: if we can use the same API key in this courier web app, that my self-care portal uses? Or should I generate a dedicated one? I'm using the free version of Hubspot, and want to keep this.
The requirements for this courier web app