OneDrive lets you back up files 'in the cloud' automatically, so that if something nasty happens to your computer (such as the hard drive failing, a ransomware attack or it being consumed in flames when you suffer a domestic fire accident) you'll still be able to access your files from another computer. You get 5 GB of storage free (which is more than you'll need if you've not got loads of big files, such as videos) and you can pay to get more storage if you need it. (That's why Microsoft provide to service; they hope that lots of people will buy additional storage space from them). The free storage limit is extended to a massive 1 TB if you subscribe to Microsoft Office 365. (i.e. if you pay Microsoft lots of money again).
Many people regard OneDrive as 'essential', whereas others have no interest in using it whatsoever:
https://askleo.com/do-i-need-onedrive/
(I've never used any form of cloud storage).
My own opinion is that if you've not used OneDrive up until now, the chances are that you'll never need it anyway (and there are plenty of other cloud storage options available, including many that offer far more free storage), so I wouldn't bother about the possibility of your OneDrive account being deleted. However if you'd like to preserve it 'just in case', simply sign into your account (using your Microsoft account details), which will tell Microsoft's servers that you're still interested:
https://support.microsoft.com/en-us/office/why-did-i-get-an-email-saying-your-account-will-be-deleted-5ee83d1a-28da-4d05-a1ca-46a522919e45