Hiding registration notice when it's registered

[dhanendran]

Description of the Change

Fixes #501. This change hides the registration notice when the valid registration key is added.

Alternate Designs

N/A

Benefits

This change will help to avoid the confusion of seeing the registration notice even after adding the valid key.

Possible Drawbacks

N/A

Verification Process

• Message should be shown when the fields are empty
• Message should be shown when invalid licence key is added
• Message should be hidden when there is a valid licence key

Checklist:

• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests passed.

Applicable Issues

#501

Changelog Entry

[dkotter]

Thanks for this @dhanendran. Left a minor comment but otherwise this looks good!

[dhanendran]

@dkotter I have addressed the spacing issue.

[dinhtungdu]

Hi @dhanendran, thank you for the PR. This PR is hiding the notice when the plugin is first time activated, where the valid_license is null, not false. Otherwise, this is ready to go.

[dhanendran]

@dinhtungdu Thanks for your suggestion. I have made the changes now.