My first attempts to reset trial time on a clean install were a no-go for me. I afterwards managed to get it working by installing the pk I provided and running portable KMSpico. I wasn't aware that was the preinstalled key, so I simply provided what worked for me.
Reinstalling a key may give an impression that system got rearmed since watermark disappears temporarily, but it does not reset the internal timer. You may even get locked out by sppsvc from installing a key on eval edition in some circumstances (error code 0xC004E01C "This evaluation product key is no longer valid."). Using slmgr.vbs -upk on anything is stupid idea and even Microsoft discourages usage of it. You can rearm eval editions 2 times with slmgr.vbs -rearm
Eval can''t be activated in the first place so just saying and on MDL you can find all the tools that are supported here https://forums.mydigitallife.net/forums/kms-tools.51/