It is not necessary to have a hard copy of the agreement if both parties have a mutual understanding. However, for future reference, it is required to have a hard copy if both parties have mutually signed it. In case a dispute arises in the future, a judicially signed copy must be available for your support.
On the other hand, if you leave the company and another person takes your place, having a hard copy will also be beneficial.
In my opinion, you should take a hard copy and store it in your files to prevent any future disputes.
Regards,
Sandeep Tomar