Nope, a legal Windows 98 requires a COA from Microsoft, which usually comes with the CD - it's not abandonware by any stretch of the imagination. You can even still buy paid support for 98 directly from Microsoft, if you ever felt like doing so.

Completely unrelated of course, there is no online activation or anything in Win98 like on WinXP, pirating back in the day was as simple as getting a valid product key

I fully expect, however, for you to purchase 98 online for the low low price of 40-60 dollars because it is the right thing to do

Edit: Of course if you do have a COA, you can use any 98 CD you can get your hands on and use it legally to install Win98 on your system.