As a new user here of SketchUp Pro, I would like to ask if the license intended for 2017 version can be use for 2018 version as the software upgraded every year? The license was bought mid-2017 so I have until Aug, 2018.
No. the same license key cannot be used for v. 2017 and 2018. You should have been sent a version 2018 serial number and key when v.2018 was introduced in November, either by the reseller you bought it from, or directly from SketchUp, if you used the web store.