German phrase
Ich würde ~ in Kontakt bleiben.
Meaning
I would like to stay in touch with ___
When to use it
It shows a wish for contact. This polite wording suits formal goodbyes.
Example dialogue
Ich würde gerne mit Ihnen in Kontakt bleiben.
I would like to stay in touch with you.
Das wäre schön. Hier ist meine E-Mail-Adresse.
That would be nice. Here is my email address.