Mesmerize License Key

I purchased Mesmerize Pro back in late 2017, early 2018. Today I updated Mesmerize Pro to version 1.6.129 and it is asking me for a license key. I believe I remember when I originally bought the theme there was no license key associated with the theme. However, they were working on it. I never thought anymore about it until now. Anybody else out there that has ran into this issue? How did you find your license key? I’m a little nervous because I checked my emails and I can’t find any receipt or anything showing where I bought the pro version. So I’m not sure how I can verify my purchase years later if they will have to do that. Any help would be greatly appreciated.