how to load previous purchases with the flutter in_app_purchase dependency

With flutter in_app_purchases 0.3.5+1 there was a simple queryPastPurchases() method, now (0.6.0) the equivalent seems to be the restorePurchases function. Should I, on every app start, execute this to determine if the user has bought my auto-renewable subscription or should I store somewhere (for example in SharedPreference) that he is entitled to my subscription services and only execute this restorePurchase function if he switches devices?