If you no longer intend to use your Here Buds with a previously paired device, you can put them into pairing mode by placing them into the case with the lid closed and pressing the reset button on the underside of the case with a paper clip 4 times in quick succession. Wait approximately 30 seconds and then open the lid. The Here Buds should flash continuously to indicate they are ready to pair.
You can then pair your Here One buds to your smartphone by opening the Here One app and following the on-screen instructions after tapping View Buds -> Pair New Buds.