Noted that there're different copywriting when it comes to setting the permission of "last seen". One uses the one mentioned here; another one is "last seen recently". The one used here is for those has no limit with related permission, so it stresses the "time is very close(less than 1 min)". "近期上过线" has the hazy meaning on the "time", which only pointed that they was online recently, maybe 1 hour, serval mins, etc. So it is not suitable.