How to Get Windows

Open CMD as Administrator

Run the following command into the cmd (keep the quotation marks in):

cscript slmgr.vbs /ipk "<serial_number>"

Tldr

Replace <serial_number> with the corresponding serial numbers below:

Home/Core                            TX9XD-98N7V-6WMQ6-BX7FG-H8Q99        
Home/Core (Country Specific)         PVMJN-6DFY6-9CCP6-7BKTT-D3WVR  
Home/Core (Single Language)          7HNRX-D7KGG-3K4RQ-4WPJ4-YTDFH  
Home/Core N                          3KHY7-WNT83-DGQKR-F7HPR-844BM 
Professional                         W269N-WFGWX-YVC9B-4J6C9-T83GX 
Professional N                       MH37W-N47XK-V7XM9-C7227-GCQG9 
Enterprise                           NPPR9-FWDCX-D2C8J-H872K-2YT43 
Enterprise N                         DPH2V-TTNVB-4X9Q3-TJR4H-KHJW4 
Education                            NW6C2-QMPVW-D7KKK-3GKT6-VCFB2 
Education N                          2WH4N-8QGBV-H22JP-CT43Q-MDWWJ 
Enterprise 2015 LTSB                 WNMTR-4C88C-JK8YV-HQ7T2-76DF9
Enterprise 2015 LTSB N               2F77B-TNFGY-69QQF-B8YKP-D69TJ 
Enterprise 2016 LTSB                 DCPHK-NFMTC-H88MJ-PFHPY-QJ4BJ  
Enterprise 2016 LTSB N               QFFDN-GRT3P-VKWWX-X7T3R-8B639

Run these last two commands to activate:

cscript slmgr.vbs /skms kms.lotro.cc
cscript slmgr.vbs /ato