How to make a master sheet of expiration dates

MyUsername30 

Without any additional information (or a copy of the workbook) it's hard to give a specific and appropriate answer. From what little you've said, I'd suggest looking at the feasibility of the INDIRECT function.

But from a design perspective, I almost always want to know why there are multiple spreadsheets; many people create multiple sheets within a workbook because that's how they tracked X --whatever it is you're tracking--when doing it on paper. But Excel can track very well, and report on distinctive components, when all the records are kept in a single database. So that would be another question I'd want to explore.

Here's a link to help you assess the applicability of INDIRECT: https://exceljet.net/excel-functions/excel-indirect-function