We will soon be releasing a NEW Qlik Sense Business Analyst Certification Exam (based on the June 2017 Release of Qlik Sense.) The first day you can take it will be January 25, 2018. You can register for it now.
If there is no compelling reason to get certified now (such as needing to meet requirements for the Qlik Partner Program), I recommend waiting until the end of January to get certified.
Qlik Certifications do not expire, but are designed to become less relevant after we release new versions of the product.
Also, there is a NEW Qlik Sense Certification Exam Study Guide which you can download from the Qlik Sense Certification web page. It's in the "Recommended Preparation Resources" section.
Certification Program Manager @ Qlik
P.S. It takes 8-10 months to develop a new certification exam, which is why the new exams are based on the June 2017 release. We plan to release a new certification every year for Qlik Sense.