Do you want to be able to prove to potential employers that you can use Lexis Library competently? Then you may be interested in taking either or both of the online tests that Lexis offer. Upon successful completion of each test a certificate will be posted out to you.
There are both Basic and Advanced levels. Basic tests your understanding of core content such as UK cases and legislation, Advanced requires an understanding of EU content and more advanced features for UK content.
More information is available at: http://www.lexisnexis.com/uk/lawschool/certification/
If you wish to refresh your mind on how to use Lexis before taking one of the tests, have a look at their online tutorials.