SCARCITY
Limited offer, Till stocks last, Limited Time are some examples of scarcity ( urgency)
To be honest I have never used this principle and hence can not give you examples on how it worked for me. But I have been a willing victim of this powerful conversion trigger many times.
Pain from loss > Pleasure from Gain
You might not use this element always on your page. When you have a “Limited Time Offer,” or a product that you can regularly create scarce offers around, it would work wonders, if it seems genuine.
See how Neil Patel, founder of Kissmetrics and Quicksprout uses it
Peep Laja from Conversion Xl says urgency works for him the best