How do I activate mail component after I purchase licence?
In short:
Copy the xml license file you received after purchase to the run folder of your application (root folder in case of web apps).
You can check the exact path using LicenseHelper.GetLicensePath() helper method.
LicenseHelper.GetLicensePath()
You can find more details here: https://www.limilabs.com/mail/afterpurchase