LumialPC :
Just asking, and also will it remove the "activate windows" watermark when you update to the insiders preview?
Insiders Program and activated valid Windows are two different things.
You can become part of the Insiders program, for free. But you are a permanent beta tester. You get any and every update they wish to push to your device.
You can't turn it off. It may break things. Not recommended to run for a primary OS on a primary system.
Start here: https://insider.windows.com/
For your current normal (non-Insider) install, to get rid of the watermark...you need to purchase a valid OS.
About $80-$100.