Are you referring to the temporary license you can get when upgrading?
If so, then yes. When you upgrade, you have the option of upgrading your existing license permanently or creating a temporary license (mind you, this is only good for 3 weeks and not a month like you have it in your question). The temp license is mostly to make sure everything looks good after the upgrade and giving you the option of testing things out before upgrading permanently.
Hope this helps,