Acrobat X Standard - serial number is not working

[AKSeaPilot]

I have used adobe acrobat for years.. maybe average once very month or 2 to just join files, maybe make a form fillable and fill it... When i installed it, it took the serial number and worked.. then every time i use it after that it no longer works and says "this serial number is not valid for this product" i am using the same install file i used years ago (i downloaded and saved it as well as my serial number) - the install is English (north america - now labeled as trial).  I DO NOT WANT to go to a subscription.. it would be a terribly expensive solution for my use scenario.. Just a month ago, my old laptop worked just fine but when i upgraded it won't anymore.. 

In addition i will note that i do not have a secure program as it hasn't had updates.. So i do not use it as default and only open a few specific pdf files with it.

What is the solution?

[try67]

We can't really help you, I'm afraid. You need to find the correct installer for your S/N. If you registered your license with Adobe it might be available under your account on adobe.com. If it's an upgrade license you must find the S/N of the previous full version you owned.

[itsmep0rk]

This is Adobe's issue.  We have 100 licenses for Acrobat X and they are deactivating randomly.  I have the original serial numbers on the cards that were issued by Adobe when we purchased the software.  the serial numbers no longer work.  your basically killing software that we paid for.