Clipboard Everywhere offers a generous Free tier. The table below shows the differences between the Free and Premium tiers.
On registration, all users are granted a 7 day free trial of the Premium tier. After those 7 days, if you don't subscribe to the Premium tier, you will automatically be placed onto the Free tier, which you can keep using for as long as you like, for free.
At the end of your trial period, your clipboard history will no longer be accessible, but will be preserved in case you subscribe in the future.