The reported wind by the tower is the relevant number.
There will be a gradient in the wind speed (often steeper at night) as the height reduces. Rapid changes in this gradient are usually referred to as windsheer and may cause an approach to be discontinued if that approach becomes unstable as a result of those changes (or indeed anything else!)
If the reported wind at touchdown is within the limit for the particular aircraft and adjusted for the relevant runway conditions, then the wind on the approach is usually within the gradient profile to complete the approach and landing.
When it isn't you throw the approach away.