M2E Pro Extension requires activation for its work. License Key activates and identifies your M2E Pro Extension. You can find the License Key-related information for your current M2E Pro in eBay Integration > Configuration > Settings > License section.
The License Key is strictly connected to the particular Domain and IP. Their validation prevents problems, such as creation of Item duplicates in case of Magento relocation. For example, duplicated Items can be created after you change the server and synchronization continue working on both old and new server. Thus, the same License Key cannot be used for different domains, sub-domains and IPs.
To obtain a License Key, press Create New License button and enter the required data. If you have already created another License Key for your Extension, you can provide it by pressing Change License button.