If it’s just tracking, then custom fields on Deals would do the trick and you can even create custom report. Now if your commission structure requires cumulative / non-cumulative tiers, blended rates, commission splits, crediting rules, quota management, crediting rollups, etc. - then this is not going to be enough. When we built Sales Cookie, we asked ourselves if we could built all the logic within HubSpot and the answer was no. There are a lot of special features required to support most commission structures (even simple ones with a quota and a few attainment tiers).