Please explain your question.
Are you asking how long you can use the Premiere Elements 14 tryout from Adobe? If that is your question, the answer is 30 days and then it expires.
If you purchase Premiere Elements 14, it is an outright purchase (no expiration date). It is not like the Adobe Creative Cloud applications which are purchased as subscriptions (monthly or yearly).
You, as customer, can have the same purchased activated serial number for Premiere Elements 14 on no more than two of your computers. And, you are not supposed to be using these simultaneously. You cannot open Premiere Elements 14 Windows projects in Premiere Elements Mac, and you cannot open Premiere Elements Mac projects in Premiere Elements Windows.
Please consider the above, give more information, and then we can give you the information that you need.