When we had a Xerox Desktop Publishing system installed at the engineering company where I worked, the installer came with a huge box of 5¼ floppies to install and configure the software. We were given a list of what functions were available, and the cost of having each one installed, and we picked what we thought would be needed and were billed accordingly.
Some time later, we decided that we needed a couple of extra functions, so a maintenance engineer came along and logged in, ticked the relevant boxes on the installation list, and logged out. I asked how this was possible, to be told that all the necessary software was actually already installed, it just needed a tick in the right box to activate it.
About a year later, I needed another function to be switched on, so I tried to log in using the original password, but it had expired. After quite a bit of cogitation, I realised that, if I were to disconnect my workstation from the server and reset the date to the previous year, the old password would let me in, I could switch on whatever I liked, and then reset the date to the correct year and reconnect to the server.
Over the next couple of years I switched on nearly all of the functions on my particular workstation, and no-one was any the wiser.
Anon because what I did was a bit naughty, and I wouldn't like to be charged retrospectively for the functions I "misappropriated".