Implement a class SoftwareLicense to manage software licenses within an IT department. Define an interface ILicensable with methods ActivateLicense$()$ and VerifyLicense$().$ The SoftwareLicense class should implement this interface and have properties such as LicenseKey, IsActive, and ExpiryDate.

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Requirements:

a$)$ Define the ILicensable interface with methods related to license management.

b$)$ Implement the interface in the SoftwareLicense class with necessary properties.

c$)$ Include methods to activate and verify a license's validity.

d$)$ Create an instance of SoftwareLicense and demonstrate activating and verifying a license.