Just look at Google. They became big by ads on the search site. Analysing the intent, not the history. If I search for a pen I want to buy a pen, thus an ad for buying a pen might be effective. If I bought a pen a day ago it is unlikely I am interested in pens for next few weeks. Look at the context of where the ad appears and match that.

To some degree that is how ads worked in print: In a magazine about horseback riding you will find ads about riding equipment, as readers are into that while reading.