Launch buttons are given to open labs. They appear, based on access being permitted to students, to instructors and to other users in the TMS. Students are permitted access to launch labs from the scheduled first day and start time of a class. An additional condition is that the student must be set to the Enrollment Status of "Enrolled" to have a launch button once class starts.
Lab access is also based on the type of lab purchased: Premium labs can be completed and relaunched, and are available 180 days after the end of class. Basic labs can be completed one time and are only available until the end of class.
During class you have access to your labs, the labs can be saved and then resumed from your Current Training or Enrollment pages. If you had the ability to launch a lab and work in the lab environment but are suddenly unable to see the Launch button on your Enrollment page anymore, the issue may be that you marked your lab "Complete" and were using a Basic lab.
When exiting a lab, you have the option to Save and Close, Cancel, or Mark Lab as Complete. Marking a lab as Complete tells the system you are finished with the lab. Once a lab is marked as Complete the system removes your completed lab instance and you no longer be able to access that lab. This is because Basic labs may not be launched again after completion.
When closing your lab instance temporarily, you should select Save and Exit or Cancel; cancelling gives you a brand-new lab environment. Save, exit or cancel allow you to launch or resume your lab. Only mark a lab as Complete when you are finished using the lab and do not want to launch it again.