easy there tom... unless proven guilty we should assume innocence although your caution is noted.
how did you purchase it? depending on how there are various ways your key could have come
http
/office.microsoft.com/en-us/access-help/find-your-product-key-for-office-2013-office-365-home-office-365-personal-office-365-university-HA102830243.aspx
if you purchased it retail then typically they can print you out a receipt even if you bought it years ago (the wonders of computers)
if you purchased it online they can do the same... or you may have an email with information on this.
to answer your question, "yes" there are ways to get your product key without needing to find that information however such things could potentially be used in a harmful manner which is why we are cautious about recommending anything but the official channels. i can however point you towards a google search
http
/bit.ly/Z1tzFl which may be of assistance.