I would like to reinstall my labtop and wanted to know whether I would be able to install a new copy without using one of the 3 activation keys - or if I somehow would be able to retract the current activation key and use the same after reinstall

Thank you for reading - Hope you can stop me from wasting an activation

if you are reinstalling upon the same machine, and that machine hardware has not changed since the previous installation, the reinstall won't consume another activation.
when you install an MS product, the activation process prepares a signature/hash of the machine hardware, and sends that hash to the MS activation servers. if that hash has not been used with the product key (e.g. a first time installation) an activation count is consumed. when the same hash and key are presented again (e.g. a reinstallation) the activation count is not consumed again.

so, your reinstallation should be no problem, assuming you've not installed/activated your Office product on too many other machines in the time since you originally installed this one.

if you do encounter an activation issue, use telephone activation and speak to an MS activation person, and explain that you are reinstalling, and they can he