There are several reasons why you may not be able to see the Edit in Browser command.
You don’t have a license.
You bought a license, but still can't see the Edit in Browser command.
Enabling the Edit in Browser command may take up to 30 minutes. If this takes too long, provide feedback to us. At the bottom of the page on the status bar, select Give Feedback.
The Edit in Browser command was available to you, but now it’s not.
There are several reasons why this can happen:
The Visio Online Public Preview has expired.
Your Visio Online license trial period has expired.
Your Office 365 admin has turned off your Visio Online license.