Approximately one year ago, I had a job interview with the CEO and the R&D manager of a company which was looking for new employees. Unfortunately, even if the interviews and selection processes were successful for me, at the end I was not hired.  

Would it be okay now to add them on my LinkedIn network (eventually, adding a dedicated connection request message), mainly to let them stay up-to-date with my career progresses and, in case, for me to not miss future hirings?