REACT Keeping the user id for later use?

We are doing the Night life app and we store the user id of people going to a bar via their user ID.

How can we store the user ID for checking later? - we are trying to write the “Remove user” from bar function but the user ID is not saved anywhere (yet).

Could we use the request somehow?

Note. The server back end seems to have access to the user id.

It would help if you could point to specific code snippets.

We solved it by using a promise. Can’t remember how. ajitsy did it.

Just wondered if there was a best practice to doing this?