@Jogs @kaljukass thanks folks for sharing your's experience... you are very kind. I will keep the memory and so far I haven't seen something unusual.
I am using this memory for almost 2 moths and there is no issue at all. Do I have to return the slot?
As explained here https://forums.mydigitallife.net/threads/ram-memory.79315/#post-1539313 you didn't get an identical module as you asked the seller but you can keep using it, but it only runs at the lower speed of the original ram module.