[SalesForce] Track history for Task Object

Create an object called AccountHistoryTracking and fields like APIName__c,OldValue__c,NewValue__c then create a fieldset on Account called'HistoryTracking' with the fields you want to track on Account and then write below code to track history on account.This way you don't need to worry about history tracking limit per object.

trigger AccountHistoryTracker on Account (after update) {

    final List<Schema.FieldSetMember> trackedFields = 
        SObjectType.Account.FieldSets.HistoryTracking.getFields();

    if (trackedFields.isEmpty()) return;

    final List<AccountHistoryTracking__c> fieldChanges = 
        new List<AccountHistoryTracking__c>();

    if(!trigger.isUpdate)
        return;

    for (Account newAccount : trigger.new) {

        final Account oldAccount = trigger.oldmap.get(newAccount.Id);

        for (Schema.FieldSetMember fsm : trackedFields) {

            String fieldName  = fsm.getFieldPath();
            String fieldLabel = fsm.getLabel();

            if (newAccount.get(fieldName) == oldAccount.get(fieldName))
                continue;

            String oldValue = String.valueOf(oldAccount.get(fieldName));
            String newValue = String.valueOf(newAccount.get(fieldName));

            if (oldValue != null && oldValue.length()>255) 
                oldValue = oldValue.substring(0,255);

            if (newValue != null && newValue.length()>255) 
                newValue = newValue.substring(0,255); 

            final AccountHistoryTracking__c accountHistory = 
                new AccountHistoryTracking__c();

            accountHistory.name         = fieldLabel;
            accountHistory.apiName__c   = fieldName;
            accountHistory.User__c      = newAccount.Id;
            accountHistory.ChangedBy__c = UserInfo.getUserId();
            accountHistory.OldValue__c  = oldValue;
            accountHistory.NewValue__c  = newValue;

            fieldChanges.add(accountHistory);
        }
    }

    if (!fieldChanges.isEmpty()) {
        insert fieldChanges;
    }
}

Setup -> Customize -> Cases -> Fields displays a "Track History" column that shows the fields for which history tracking is turned on and has a "Set History Tracking" button to change these. You can select the HTML and e.g. paste it into Excel.

Is this not sufficient for your needs?