Code:
[HKEY_CURRENT_USER\Software\Microsoft\Notepad]
"Integration"=dword:xxxxyyyy
xxxx = usage days (different consecutive days)
yyyy = install date (days since 1900)
"Integration"=dword:0015a99b = 21 days, installed on 15 nov. 2018
didn't stay on it too much, so other things might be there