Hi @anettszs , welcome to the QuEra Forum!
The maximum allowed running time on Aquila is 4 microseconds. Unfortunately this is a hard limit and there is no way of extending this.
I’m not quite sure I understand what you mean by “gradients”, could you please elaborate?
As for other ways to access Aquila, Amazon Braket is currently the only publicly facing method we have. There are other SDKs you can use but they will still connect to Aquila via Braket.
Hope that helps!