Eventually found the answer. (NOTE: STContains works ONLY in MS SQL Server 2012 or greater)
-- First point
declare @p1 geography = geography::STGeomFromText('POINT(-114.110043 51.067222)', 4326);
-- Second point
declare @p2 geography = geography::STGeomFromText('POINT(-113.850491 51.100004)', 4326);
-- Find the distance between points in meters
declare @distanceInMeters float = @p1.STDistance(@p2);
-- Create circle geography object
declare @cicleGeography geography = @p1.STBuffer(@distanceInMeters)
declare @p3 geography = geography::STGeomFromText('POINT(-112.850491 51.100004)', 4326);
-- Returns true if the third point is inside the circle
select Id, @cicleGeography.STContains(@p3)
Very easy :)