I installed Microsoft SQL Server 2014 a couple of months before on my PC, but now I suddenly found that the evaluation period has expired and a message appears when I try to open SQL Server Management Studio:
Evaluation period has expired. For information on how to upgrade your evaluation software please go to http://www.microsoft.com/sql/howtobuy. I seem to find a easy solution to this problem.
4: Accept the license terms.
5. Specify the instance of SQL Server to modify.
7. Do not lose your patience at this stage here since you might just have to wait for a couple of minutes without having to do anything but to wait for the next screen to appear. (I nearly aborted this process at this stage when I felt like it was not happening as expected. )
I hope this was helpful. Comments and feedbacks are welcome.