How Streams provided by watch() are managed?

[givip]

If I simply cancel subscription is it enough to right memory management?
If I call watch multiple times is it returns the same stream or the new one?

[simolus3]

If I simply cancel subscription is it enough to right memory management?

Yes, moor will evict cached data shortly after the last listener detaches from a stream.

If I call watch multiple times is it returns the same stream or the new one?

If you call watch() while another listener is active, the stream will be re-used. You might get a different stream instance, but they will be powered by the same underlying StreamController. Further, moor will cache the latest value of a stream so that the query won't be run if it's not necessary.