Only 1 ram slot available, so yeah, 1st one appears to be soldered.
R558UQ-DM540D Golden, Nov 2016 is month of Mfg and Import.
From Emall Kolkata, Chandni. IT ARENA (Bardroy infotech) on 1st floor, they quoted the lowest.
RAM I got one from Amazon.in, Adata DDR4 2133,8GB...Its still on...