The data sampling limit of GA premium is approx. 200 times than that of standard GA which means you get more unsampled data in GA premium than in GA standard. Use an alternative analytics tool such as Matamo. Matomo does not have any data sampling limit. Yes, you heard it right. This is because all of the data resides on your server. Other ways to prevent data sampling include always keeping the data sampling setting in GA to ‘Greater precision’, avoid using advanced segments and/or secondary dimensions,  run your report in such a way that your report is based on the biggest possible percentage of total website session.