The machine has only one standard Laptop slot for the new DDR4 Memory. It is not soldered in, but difficult to get to.
This memory is not easy to upgrade. There is no simple cover for the RAM access.
In order to increase the RAM, you basically have to disassemble the laptop, remove the battery, DVD drive, Keyboad and bottom base to get to the memory slot.
Lenovo ships it with 4 GB and says it upgradable to 8 GB.
However, Crucial memory sells a single 16 GB stick which they say is compatible. I would call Crucial if you want to upgrade above the 8 GB limit that Lenovo states this machine has.
If you use the Crucial product finder to pick your product, and it doesn't work in your machine, they will either help you on the phone to get it to work, or refund your money.
This is the tech info from the Lenovo Web Site:
Memory
Type and speed: DDR4-2133 MHz
Maximum supported capacity: 8 GB
Slot: SODIMM × 1
This is the tech info from the Crucial Web Site:
Your Lenovo IdeaPad 110-15ISK
system specs as shipped
memory
Maximum Memory:20GB
Slots:1 (1 bank of 1)
*Not to exceed manufacturer supported memory.
Here is Crucial's 16 GB Stick:
Crucial 16GB DDR4-2133 SODIMM
CT9434429
DDR4 PC4-17000 • CL=15 • Dual Ranked • x8 based • Unbuffered • NON-ECC • DDR4-2133 • 1.2V • 2048Meg x 64 •
upgrade for Lenovo IdeaPad 110-15ISK system.
Here are the upgrade instructions from Lenovo:
1090 DIMM
For access, remove these FRUs in order: • “1010 Keyboard” on page 33 • “1020 Optical drive” on page 35 • “1030 Base cover” on page 36 • “1040 Battery pack” on page 40
Figure 9. Removal steps of DIMM Release the two latches on both edges of the socket at the same time in the direction shown by arrows 1, and then unplug the DIMM in the direction shown by arrow 2.
When installing: Insert the notched end of the DIMM into the socket. Push the DIMM firmly, and pivot it until it snaps Into the place. Make sure that it is firmly fixed in the slot and difficult to move.
Hope this answers your question.