how to check if my H1 petition extension got filed under premium?

My employer had filed my extension last month for my petition that expires next month. Now they are saying they have changed to premium. How do I check if my extension has changed to premium? I have the older receipt number. Does the receipt number change?

No, it does not change, the receipt number will remain the same. The lawyer should have received a receipt stating that the application for premium petition was received through email within 3 days of USCIS receiving your request for premium. You can ask for the email receipt.

Does the receipt mention it was done in premium? and would it have my details on it?

The email receipt would have your name and receipt number for which premium was applied and also a hard copy of the receipt notice will be sent to your lawyer. Within 15 days you should receive your decision.

The final H1 approval notice would not mention of the premium.