Now one thing I have done in the past is when the COA sticker is getting pretty worn is to make up a small amount of two pack glue something like Araldite (the five minute cure stuff is ideal) which dries clear and spreading a thin layer of this over the sticker and like wetting things sometimes makes the detail/letters more legible. The added bonus is the sticker is protected forever by the hardened glue
Note
The below is my personal subjective opinion and as such not intended to be taken personally, nor should it be taken as critic.
I've never had this issue. Whenever I get a new laptop or desktop with a pre-installed Windows, or software with a key sticker in the box, I take a photo of that, paste it to OneNote with additional information about for which device / software package it belongs. OneNote syncs this information to my OneDrive, from where I can always find the information when needed.
I do the same with serial and product keys received per email; I copy & paste the information to OneNote.
To "backup" this information I write the same in an Excel workbook, which is also synced to my OneDrive.
For me, a story like "my COA sticker is unreadable, please give me a key" is either a story about a lazy user or a try to get a pirated copy of Windows activated.
Kari