"License already in use"

[Svenja5E45]

My Adobe Acrobat Professional DC 2017 Version told me that my licence ends soon. I suspect that this has something to do with the fact that I had to reinstall everything on my pc. Maybe it doesn't recognise that I have purchased a normal licence already some time ago (I think it was some kind of student-teacher-license). I tried to enter the licence number in my account since - for some reason - it wasn't listed as registered there. However, it won't register as "this number is already in use". Which is of course correct because it is in use BY ME and rightfully so. Can anybody help me?    

[kglad]

if you purchased from or registered with adobe, check your account, https://accounts.adobe.com and see if you can sign-out/deactivate all the computers listed.

if you can, then you can reinstall on your "new-appearing" computer.

if you cannot, you'll need to ask adobe support for an activation count reset:  using a browser that allows popups and cookies, contact adobe support during pst business hours by clicking here, https://helpx.adobe.com/contact.html

click contact us (in the lower right)
in the chat field, type AGENT
be patient, it can take quite a while to reach a human.  immediately ask for an activation count reset (which will deactivate all current installations).