Typically you should just enter your activation code one time only. There are a few possibilities that could cause a prompt to re-activate the license.
The Numerical Cloud license is typically located in the users Roaming folder, "C:\Users\<Your User Name>\AppData\Roaming\NumericalCloud". If you switch users (on the same computer) or the "Roaming Folder" is deleted or changed could be a reason for the re-activation prompt. You can verify/change where the Numerical Cloud license is stored by going to menu: Setup | Options..., select tab "Misc", and see "Numerical Cloud Folder".
A “proxy server” is typically used to block access to the Internet by Local Area Network (LAN) users unless they are authenticated with a user name and password. If our software resides behind a proxy server then Internet access will also be blocked for the license activation system.
Invalid Password (avoid using punctuation marks and symbols such as @, &, and *, for example) :
For your activation Password please keep it simple and only use characters: 0-9, a-z, A-Z (avoid using punctuation marks and symbols such as @, &, and *, for example).