Hi @Sara Aghaeian,
did you already install your Jira?
If yes, you can access your server id in the "administration" > "system" > "system info" part. Have a look in the "Jira info" section for "server ID"
If you don't have it installed yet, you can see it during the installation when you select the option "I have a Jira key" as described in this post.
I think, we need some background information here.
Jira is a software which you either install on a server somewhere in order to use it or you can get Jira cloud which Atlassian will run for you. You can then access Jira typically via a browser like Chrome, Firefox or Safari.
If you use Jira Cloud, you can also use the Jira Cloud app for iOS in order to access your data.
With that background info, I'd like to ask you where you actually bought Jira and based on your question why you need a service ID? Could you provide some more background information what you did here? Screenshots might also help.
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