Here is my two cents worth..
I'm sorry for the inconvenience to you by the Pop-up Advertisement..
You did choose to use the FREE product, and It cost a lot of Money in Man hours and production cost for Software Companies to produce and Upgrade Security software..
So to offset the Cost, and afford to provide a Free or Trial Version of their Products,
Most Software Developers, use one of Several methods to off-set that cost..
1.) Provide a Trial version with a Built-in Drop Dead Shut off time limit, that forces you to Buy the product,, or
2.) Produce a Trial Version that Reverts to a Limited Function Free version with Constant Pop-up Advertisements to entice the Free User to Try the Paid Version..
3.) or Do not offer any Free version at all..
IMHO, the occasional Pop-up is a small price to pay for the Use of a FREE product that you depend on to Protect your computer..