If you are on a subscription plan, your subscription period may have finished. You will have to renew your subscription in order to continue using Geneious. For more information, see How does a Geneious Prime subscription plan work?
If you've recently renewed your subscription plan but your license expiry has not been extended, please see the following post: I renewed my subscription but my license expiry hasn't been extended.
If you have a perpetual license, it may not be valid for the version of Geneious you are trying to run. You may need to purchase an upgrade for your license to use the latest version of Geneious.
Post updated 4 April 2016