Perpetual licenses are single-user licenses for WrapR 2018 each priced at $69.
Perpetual Licensing means you own the software and are entitled to any maintenance releases to that version of the software.
Yes, if you have a license for a previous version and wish to upgrade you can at reduced cost.
Up to 3 devices can use the license.
No, SketchUp continuously evolve their software development kit. Future verions of SketchUp may break something in older versions of WrapR. WrapR will always work of the versions of SketchUp it supports for that release.
Your license entitles to any updates to the current version you purchased. If you purchase WrapR 2018 you will get all updates we issues for free for that version. WrapR 2019 will require to upgrade at reduced cost.