I am building an application that I intend to market broadly accross many companies. 

1) Set up a Remote Application on my Salesforce instance

2) Create a website that allows anyone to go through the OAuth flow with my application credentials

3) Use the RESTful API to access a user's Salesforce data

I am confused as to where I run into API limits...am I limited on my ability to make calls to the API using my application key? Or will my application use up the limits of my customer's Salesforce instances? I need my application to be agonstic to the particular edition my customer is using.

Thanks.