UPDATE 2022

Windows now has multi-slot clipboard built-in. It is great.

Multi-slot Copy Paste

Source: Damogran Labs: https://damogranlabs.com/
Date: 16.11.2018
Version: 1.2

About

This project enable you to use copy/paste feature on up to 9 separate slots.
Based as script on AHK for Windows, but standalone executable can be found on Damogran Labs SourceForge.

How to use

• COPY: Set slot data with Left CTRL + WINDOWS + Numpad 1-9.
• PASTE: Recall slot data with Left CTRL + ALT + Numpad 1-9.
• RESTORE: Restore previous clipboard content with Left CTRL + ALT + Backspace. 
• INSPECT: Display all slots content in popup window with: Left CTRL + ALT + Numpad 0

It does not interfere with standard Windows Ctrl + c and Ctrl + v - you can still use it for files, images, text.
Other slots are meant for text only.

Can I customize it?

Yes, of course. Edit 'multislotCopyPaste.ahk' according to AHK docs.
If you simply wish to change keyboard shortcut mapping, you need to modify lines starting with:
<^<#Numpad1:: and <^<!Numpad1:: In this case, '<^'stands for left control, '<#' for left windows, '<!' for left Alt and NumpadX is self-explanatory. As long as you stick to AHK syntax and don't interfere with other windows/program shortcuts, you are fine. Remember to restart AHK script ofter saving.

Run on startup?

Press 'Win + R' and paste: %appdata%\Microsoft\Windows\Start Menu\Programs\Startup Than just create shortcut to .ahk or .exe file.