How to use getAccessToken properly

I’m using okta-react in my React app with the OktaSignInWidget.
I was wondering about the proper use of WithAuth.getAccessToken.
Should I call this method for every action which requires authentication? Or can I get it once after login, keep it in store and use it from there?
If it’s fine to get it just once than I have a follow up question: How to get the accessToken on login?
That is I want to get it as a response to a successful login and store in my state management (I’m currently using the signInWidget, but will change it if needed).

Thanks a lot in advance!