some people reporting their Sumo license doesnt work anymore.
i just upgraded a new computer and installed just fine.
make sure you used the proper
Registered by
Registered key

I have multiple licenses from them so heres what i learned:
if you bought
1) WebSite Auditor from AppSumo use the license starting with WA------
2) if you bought Power Suite SEO bundle directly, use the license starting with LA------
3) if you bought SEO SpyGlass ltd from somewhere use the license code with SSG--------

the Registered by has to match!!

no affiliation or anything, just Sumoling to Sumoling here... hope it helps for those saying it doesnt work anymore, coz it does!