If you run into any issues related to your license key activation   Please  check  if you installed  both Community Edition plugin ( CE ) and the Premium Version.  As part of our product enhancement we have created a  version  where we split the WPBackItUp Community Edition(CE) formerly known as    Lite plugin ( free version) and Premium plugin. We highly recommend that you reinstall the premium plugin with the  release of  new version,  It is expected that you can better use the   features of premium plugin and enjoy the benefits in the long run, Moreover we would like to lessen issues for users and support. 

Then you can Update your License information in WPBackItUp License Info then click the "Update" button.

Dashboard License Info

If you need further assistance Please contact WPBackItUp Support and submit a support ticket.