Gate

[xavier c]

if you use the spell Gate to call a extraplanar creature of lower HD then your caster level and control it how long does it remain in your service

[Rynjin]

Well, it directs you to Lesser Planar Ally for rewards, and the rewards are based on the time spent.

Planar Ally wrote:

A task taking up to 1 minute per caster level requires a payment of 100 gp per HD of the creature called. For a task taking up to 1 hour per caster level, the creature requires a payment of 500 gp per HD. A long-term task, one requiring up to 1 day per caster level, requires a payment of 1,000 gp per HD.

So, up to 1 day per caster level.

[xavier c]

but on the d20pfsrd it also says that if the creature has lower HD then your caster level you can control it for free

[Rynjin]

No, it doesn't. At no point does it say that.

In fact, it contains this line:

"This use of the spell has a material cost of 10,000 gp in rare incense and offerings. This cost is in addition to any cost that must be paid to the called creatures."

The only mention of creatures lower than your HD is here:

"In the case of a single creature, you can control it if its HD does not exceed your caster level."

I could see how you might take that to mean it was for free, if not for the immediately proceeding line:

"A creature with more HD than your caster level can't be controlled."

Which very clearly defines the context of the other sentence.

[Ravingdork]

"I control you to not accept any reward."

Pretty simple that.