Moreover, there are two possible issues that are why the license automatically deactivated.
1. If your server has any caching system or you are using any 3rd party caching system like Cloudflire then it’s didn’t save the changes when you activating the license. Please turn off the caching system to activate the license.
2. If you are using a caching plugin then it also doing the same.
Please Note: There is nothing on our end that will deactivate the license automatically without any reason.