Sure, here's a possible SQL query that should do what you want:

```
SELECT StockID, MAX(Price) AS MaxPrice
FROM MyTable
WHERE Date >= DATEADD(day, -7, GETDATE())
GROUP BY StockID;
```

This query selects the `StockID` and the maximum `Price` for each stock that has had any price update in the past 7 days (relative to the current date and time). To achieve this, we filter the rows of the table using the `WHERE` clause, which selects only the rows for which the `Date` is within the last 7 days. We then group the results by `StockID` and apply the `MAX` function to the `Price` column to obtain the highest value for each group. Finally, we use the `AS` keyword to rename the output column as `MaxPrice` for clarity.
Data una tabella dei prezzi giornalieri delle azioni con le colonne StockID, Date e Price, scrivi una query SQL per trovare il prezzo massimo per ciascuna azione negli ultimi 7 giorni.