Serial Number with Asset Store Purchase

Hi, I'm very new to the Unity ecosystem so excuse me if this is a silly question.

If I publish something on the asset store, can I provide a unique serial number with each purchase?

I am hoping to publish an asset on the store that will connect via our Server to Googles voice recognition and NLP services.
(This is basically a front end port of something we have developed on other platforms)

Our server has to be there as the google API keys should not be exposed within a front end app. So anyone who downloads the asset will need to go to our server and upload the relevant google API keys.

However, I need a way to tie usage to contact details, and purchase. The load on our server will be very low per request, but if someone had a hit app with this asset it could get quite costly for us on the sever side.
So i'm trying to find the best business model to mitigate this risk.

My current thoughts are to have usage limits on the server side (and in the asset T's and C's) and way to for us to contact anyone exceeding these limits, and strike up a deal with them to pay for expanded server capacity. But I'm open to other solutions.

Any other ideas welcome. Many thanks.

 

I think Unity lets you validate order numbers and have a way to automate that, maybe an API or something, I don't use it personally.