P1 is the perpetual license level allows to run Cloud Hosted Router (CHR) indefinitely. It is limited to 1Gbps upload per interface. All the rest of the features provided by CHR are available without restrictions. It is possible to upgrade P1 to P10 or P-Unlimited. After the upgrade purchased the former license will become available for later use on your account.
Perpetual is a lifetime license (buy once, use forever). It is possible to transfer a perpetual license to another CHR instance.
Cloud Hosted Router (CHR) is a RouterOS version meant for running as a virtual machine. It supports x86 64-bit architecture and can be used on most of popular hypervisors such as VMWare, Hyper-V, VirtualBox, KVM and others. CHR has full RouterOS features enabled by default but has a different licensing model than other RouterOS versions.