This problem is quite common, especially if the license was purchased a long time ago or used on another device. I am familiar with your situation, and I managed to solve it using the
kms tools activator. This tool allows you to temporarily activate Windows without having to buy a new key. The process is quite simple: download the KMS Tool, run it, and the system is automatically activated via the KMS server. The tool works stably and effectively, the main thing is to follow all the instructions and use it only from the official website. As a result, I was able to use my Windows again without problems and without spending money on a new key.